Technical Fiat Punto 1.2 16V mk2b (I guess) several issues

judderbar · Apr 17, 2018

I have a 2004 1.2 16V punto.

I have an old key without the transponder which turns on the ignition and cranks the engine with the key code light on. The fuel pump runs normally with this key even when the key code light is on.

So where are you now with this problem? Is it now fixed after reconnecting various connections?

It sounds like you had multiple problems caused by bad wiring somewhere and the most obvious cause of multiple problems is bad earths where nearly all major earths go back to a playing card shaped box just in front of and under the battery.

The engine ECU is on top of the air inlet it has two big plugs and thick wiring. The Earth on one of the 4 screws for the ECU needs to be in good condition.

The pump is under the rear seat. The fuel pump relay is the red relay nearest the wing in the engine fuse box. If you remove the relay and bridge the large connections in the fuse box which are normally under the relay the pump should run. There is a continuous positive wire from the relay connections to the fuel pump. The earth for the pump goes via an impact switch just inside the carpet in the passenger area under the glove box. So if you turn on the car and the pump does not run you can test these connections to isolate the problem. An ECU/ECU Earth problem or wiring connection that impacts the ECU will be isolated if the pump runs with the relay bridged but it does not run for a few seconds when you first turn on the ignition.

mkey · Apr 17, 2018

Bill, I don't see anything else in there having a large connector and I think I managed to account for most of the wiring.

There is a big wad of wires coming from the cockpit. It splits three ways; part of the wires goes toward the fuse box, part goes toward headlights and the last part is connected to the servo pump, or whatever that is. One of those large connectors is coming from the cockpit, the other goes toward the engine.

I have lifted the air filter from the engine top and is something I'd consider to be plugs.

Thanks for clearing up that "wiggle in the lock" issue.

There are some screws below the turning wheel, I can try taking that apart and see what I can see. Neither key I'd consider damaged, I did drop my key a few times (once on the parking lot, it went right in the middle below the car, once just now when I was returning to my apartment lol) but it's covered in quite elastic rubber so I'd wager it's somewhat shock proof.

Still for me, to get both at once suggests poor contacts inside the switch.

Which switch are we talking about?

judderbar, near the battery I have two earths, but I can't see the playing card shaped box. On previous images you can see this "main" earth, to which the negative of the battery and the gearbox (as far as I understand) are connected. This connection looks solid to me. Close to that spot, there is another grounding connection where thinner cables are connected. This connection does not look that solid and it appears to be connected to an area which has been painted over. To the right is this ground of questionable quality. I'd love getting some advice on how to improve that.

The engine ECU is on top of the air inlet it has two big plugs and thick wiring. The Earth on one of the 4 screws for the ECU needs to be in good condition.

We're probably not thinking about the same thing. I have an air filter fitted on the top of the engine, but where is the air inlet supposed to be? The air filter has a part that is missing, looks like a plastic pipe should be fitted there but it must have been discarded when the car was repaired initially.

The pump is under the rear seat. The fuel pump relay is the red relay nearest the wing in the engine fuse box. If you remove the relay and bridge the large connections in the fuse box which are normally under the relay the pump should run. There is a continuous positive wire from the relay connections to the fuel pump. The earth for the pump goes via an impact switch just inside the carpet in the passenger area under the glove box. So if you turn on the car and the pump does not run you can test these connections to isolate the problem. An ECU/ECU Earth problem or wiring connection that impacts the ECU will be isolated if the pump runs with the relay bridged but it does not run for a few seconds when you first turn on the ignition.

I have lifted the back seat and found a plastic cover right in the middle and there's a rubberized opening through which a number of wires go somewhere under the carpet. I'd like some more explanations before following these steps you have layed out.

What does "nearest the wing" mean? What's an impact switch?

Current situation

Things worked great till this afternoon. After lunch I went down to the car to fiddle some more with it and, well, we're back to square one. I tried using both keys, no difference between them. I tried turning ignition on about 2 dozen times, turned on the engine two times. Mostly the same scenario, "key coding" light on, pump remains silent.

I tried cranking just a few times and the engine didn't start under pump off/"key coding" on conditions. I tried using both keys I have; inserted them slowly, quickly, turned them around and whatnot, no change.

On a few occasions I could hear the pump operate for just a second, shorter than usual, the "key lamp" was left on and the engine would not start.

After the engine did start, I left it running for a few minutes. Sometime during the operation the "check engine" and "key coding" lights turned on, however I did fiddle a bit around with the wiring while the engine was running. Upon turning it off and turning the ignition on some more, I managed to get the pump to function and no "key coding" light about 5-6 times in a row. After that I was back to pump off, light on.

Last note, the lights I usually get are "battery charge," "check engine," "check oil" and "key coding." During these last tests, however, I'd mostly just get "battery charge" and "key coding" while the other two would turn off while I kept the ignition off.

Once again, thank you both, I really appreciate your dedication to this crap.

LeoAchaicus · Apr 18, 2018

Αfter two (2) different professional mechanics and one (1) professional electrician have worked on your car and have failed to fix it, thinking that you will fix the car by taking advice from random people on the internet does not make any sense.

I wish you luck in fixing your car on your own but I don't think it's gonna happen anytime soon.

jackwhoo · Apr 18, 2018

Don't put both keys on same key ring , it will cause immobilizer to not always switch off.

judderbar · Apr 18, 2018

mkey said:
Bill, I don't see anything else in there having a large connector and I think I managed to account for most of the wiring.

There is a big wad of wires coming from the cockpit. It splits three ways; part of the wires goes toward the fuse box, part goes toward headlights and the last part is connected to the servo pump, or whatever that is. One of those large connectors is coming from the cockpit, the other goes toward the engine.

I have lifted the air filter from the engine top and is something I'd consider to be plugs.

Thanks for clearing up that "wiggle in the lock" issue.

There are some screws below the turning wheel, I can try taking that apart and see what I can see. Neither key I'd consider damaged, I did drop my key a few times (once on the parking lot, it went right in the middle below the car, once just now when I was returning to my apartment lol) but it's covered in quite elastic rubber so I'd wager it's somewhat shock proof.

Still for me, to get both at once suggests poor contacts inside the switch.

Which switch are we talking about?

judderbar, near the battery I have two earths, but I can't see the playing card shaped box. On previous images you can see this "main" earth, to which the negative of the battery and the gearbox (as far as I understand) are connected. This connection looks solid to me. Close to that spot, there is another grounding connection where thinner cables are connected. This connection does not look that solid and it appears to be connected to an area which has been painted over. To the right is this ground of questionable quality. I'd love getting some advice on how to improve that.

View attachment 189984

View attachment 189985

The engine ECU is on top of the air inlet it has two big plugs and thick wiring. The Earth on one of the 4 screws for the ECU needs to be in good condition.

We're probably not thinking about the same thing. I have an air filter fitted on the top of the engine, but where is the air inlet supposed to be? The air filter has a part that is missing, looks like a plastic pipe should be fitted there but it must have been discarded when the car was repaired initially.

The pump is under the rear seat. The fuel pump relay is the red relay nearest the wing in the engine fuse box. If you remove the relay and bridge the large connections in the fuse box which are normally under the relay the pump should run. There is a continuous positive wire from the relay connections to the fuel pump. The earth for the pump goes via an impact switch just inside the carpet in the passenger area under the glove box. So if you turn on the car and the pump does not run you can test these connections to isolate the problem. An ECU/ECU Earth problem or wiring connection that impacts the ECU will be isolated if the pump runs with the relay bridged but it does not run for a few seconds when you first turn on the ignition.

I have lifted the back seat and found a plastic cover right in the middle and there's a rubberized opening through which a number of wires go somewhere under the carpet. I'd like some more explanations before following these steps you have layed out.

What does "nearest the wing" mean? What's an impact switch?

Current situation

Things worked great till this afternoon. After lunch I went down to the car to fiddle some more with it and, well, we're back to square one. I tried using both keys, no difference between them. I tried turning ignition on about 2 dozen times, turned on the engine two times. Mostly the same scenario, "key coding" light on, pump remains silent.

I tried cranking just a few times and the engine didn't start under pump off/"key coding" on conditions. I tried using both keys I have; inserted them slowly, quickly, turned them around and whatnot, no change.

On a few occasions I could hear the pump operate for just a second, shorter than usual, the "key lamp" was left on and the engine would not start.

After the engine did start, I left it running for a few minutes. Sometime during the operation the "check engine" and "key coding" lights turned on, however I did fiddle a bit around with the wiring while the engine was running. Upon turning it off and turning the ignition on some more, I managed to get the pump to function and no "key coding" light about 5-6 times in a row. After that I was back to pump off, light on.

Last note, the lights I usually get are "battery charge," "check engine," "check oil" and "key coding." During these last tests, however, I'd mostly just get "battery charge" and "key coding" while the other two would turn off while I kept the ignition off.

Once again, thank you both, I really appreciate your dedication to this crap.

in your second picture there is a bundle of small black wires. Without looking at my car I am guessing these are the earth wires connected to that 'playing card' shaped block. I can check this tomorrow.

If you crash the car the impact switch turns off the petrol pump.

The left wing is the metal thing that goes over the wheel between the door and bumper. So the red relay nearest that wing is the petrol pump relay.

As for testing the pump, if you have no idea what you are doing it is going to be a bit difficult to do it. Your problem seems to be the earth wires at the front of the car. Be systematic. If you turn on the ignition and you get no petrol pump sound then pull out the red relay nearest to the left of the car when in the drivers seat and bridge the large contacts. If the pump runs then it sounds like wiring to the engine ECU is at fault.

The engine ECU is not hard to find. Follow the path of the air and you will find in one location there is a metal thing with two electrical plugs and thick bundles of wires. It is to the right of the air intake manifold .

mkey · Apr 18, 2018

jackwhoo said:
Don't put both keys on same key ring , it will cause immobilizer to not always switch off.

They are always kept separately.

mkey · Apr 18, 2018

judderbar said:
in your second picture there is a bundle of small black wires. Without looking at my car I am guessing these are the earth wires connected to that 'playing card' shaped block. I can check this tomorrow.

I don't have a block, that bit of metal plate seems to have been welded on and painted, that part of the car supposedly suffered the most in the crash. Please, do check, I can use more information.

judderbar said:
If you crash the car the impact switch turns off the petrol pump.

I figured that one out later. I haven't managed to find it near the glove compartment box, though. I can't see anything in that area, there is something below the console on the co-driver side, there's a moderately exposed connector, you could kick it with your foot easily if you were so disposed.

judderbar said:
The left wing is the metal thing that goes over the wheel between the door and bumper. So the red relay nearest that wing is the petrol pump relay.

As for testing the pump, if you have no idea what you are doing it is going to be a bit difficult to do it. Your problem seems to be the earth wires at the front of the car. Be systematic. If you turn on the ignition and you get no petrol pump sound then pull out the red relay nearest to the left of the car when in the drivers seat and bridge the large contacts. If the pump runs then it sounds like wiring to the engine ECU is at fault.

I fiddled around the pump today.

Although the top of the pump is quite dusty, the connector is completely clean on the inside. The fatter yellow/purple wire is going from the pump to the cockpit fuse box, I checked that connection with my multimeter. I think the thinner blue wire is on the other connector, however I couldn't get into that tight pin to check. I'm assuming the other fatter purple cable is grounded somewhere to the chassis, but I don't know where.

Are you saying the top left red relay is turning on the pump? I didn't want to fiddle with this on my own since I didn't know which relay does what exactly.

judderbar said:
The engine ECU is not hard to find. Follow the path of the air and you will find in one location there is a metal thing with two electrical plugs and thick bundles of wires. It is to the right of the air intake manifold .

OK, I'll check again. Are you quite certain it's not in the fuse box? On the fuse box cover it says "centralina" which is Italian for "ECU". Even if it says so only in Italian lol English translation does not mention it.

Other things I did today. I tried to check the ground in the engine area on various points by measuring voltage between the positive side of the battery and various points which all should be grounded. While the alternator was charging, I measured 13.99V on any point I touched with my lead. It figures that if the ground was bad somewhere, a voltage differential should have been visible somewhere, but it wasn't.

The engine ignition acted more erratically today, the pump would barely operate and the lights selection on the dashboard varied from "check engine+check oil+battery charge+key coding" to only "battery charge" being on. I tried starting the engine a few times, it would not. However, without lingering with the key in the ignition position and proceeding directly to start the engine, it started with no problems two times in a row. From this I jump to a conclusion that this may be a racing condition of sort, which by definition has a random outcome.

I also tried checking the aerial, which I assume is what I pointed out below the lock, but I doubt that connector is loose since I couldn't even unplug it. Is there maybe a way to disable the whole "aerial+transponder" thing and make the ECU think everything is OK with the key at all times? I ought to find an experienced car booster lol

judderbar · Apr 20, 2018

mkey said:
I don't have a block, that bit of metal plate seems to have been welded on and painted, that part of the car supposedly suffered the most in the crash. Please, do check, I can use more information.

I figured that one out later. I haven't managed to find it near the glove compartment box, though. I can't see anything in that area, there is something below the console on the co-driver side, there's a moderately exposed connector, you could kick it with your foot easily if you were so disposed.

I fiddled around the pump today.

View attachment 189998

View attachment 189997

Although the top of the pump is quite dusty, the connector is completely clean on the inside. The fatter yellow/purple wire is going from the pump to the cockpit fuse box, I checked that connection with my multimeter. I think the thinner blue wire is on the other connector, however I couldn't get into that tight pin to check. I'm assuming the other fatter purple cable is grounded somewhere to the chassis, but I don't know where.

View attachment 190000

Are you saying the top left red relay is turning on the pump? I didn't want to fiddle with this on my own since I didn't know which relay does what exactly.

OK, I'll check again. Are you quite certain it's not in the fuse box? On the fuse box cover it says "centralina" which is Italian for "ECU". Even if it says so only in Italian lol English translation does not mention it.

Other things I did today. I tried to check the ground in the engine area on various points by measuring voltage between the positive side of the battery and various points which all should be grounded. While the alternator was charging, I measured 13.99V on any point I touched with my lead. It figures that if the ground was bad somewhere, a voltage differential should have been visible somewhere, but it wasn't.

The engine ignition acted more erratically today, the pump would barely operate and the lights selection on the dashboard varied from "check engine+check oil+battery charge+key coding" to only "battery charge" being on. I tried starting the engine a few times, it would not. However, without lingering with the key in the ignition position and proceeding directly to start the engine, it started with no problems two times in a row. From this I jump to a conclusion that this may be a racing condition of sort, which by definition has a random outcome.

View attachment 189999

I also tried checking the aerial, which I assume is what I pointed out below the lock, but I doubt that connector is loose since I couldn't even unplug it. Is there maybe a way to disable the whole "aerial+transponder" thing and make the ECU think everything is OK with the key at all times? I ought to find an experienced car booster lol

You need to focus on one thing at a time.

1. The first thing to notice is you have many problems where many problems are likely to be caused by one problem related to a bad earth.

2. The pump should always operate with or without the ignition on if you bridge the large contacts of the relay I have my finger on. If that does not happen it is quite simple to investigate why it does not run every single time.

3. Given the crash damage it seems possible there is a problem with the multi earth box I have put my finger on next to the lights. The wiring is possibly perfectly fine and it just needs the single earth of the earthing box connected to the metal of the car via the bolt to be in working order

4. I have my finger on the earth of the engine ECU which has the two plugs and thick bundles of wiring. That earth needs to be in good condition.

mkey · Apr 20, 2018

judderbar said:
You need to focus on one thing at a time.

I agree 100%.

1. I certainly hope so.

2. I'll give that a try now. I just didn't want to do it before because I wasn't sure which relay did what.

3. I don't have that earth box. As I have shown with a picture before, it's just a bolt and two bundles of wires connected together. Maybe this car model doesn't have such earth box or it was removed during the "repair."

4. I can definitively not see anything like that under the hood of my vehicle.

I'll take some more pictures and get to you in a few minutes.

mkey · Apr 20, 2018

OK, I found the ECU, it's behind the air intake, toward the cockpit. I'm not sure what I'm supposed to check there. I removed one of the connectors, it looks clean and really solid. I'm not certain where's the ground connection on the ECU, but I guess it's the whole surface which is tightened down with a number of screws. It's a really inaccessible location.

I removed that red relay on the right and the pump went on working without it. So, as my brother pointed it out, I looked at the schematic on inner side of the relay box cover and there it states that red relay controls the heater fan.

Here http://fusesdiagram.com/fiat/fuses-and-relay-fiat-punto-2.html it states that the fuel pump relay is a black relay on the left side, however I don't have that one. So I'm assuming that's meant for diesel engines.

I also rechecked that ground connection (post#22,) it appears to be quite tight and I can't measure any voltage drop on it.

judderbar · Apr 20, 2018

mkey said:
OK, I found the ECU, it's behind the air intake, toward the cockpit. I'm not sure what I'm supposed to check there. I removed one of the connectors, it looks clean and really solid. I'm not certain where's the ground connection on the ECU, but I guess it's the whole surface which is tightened down with a number of screws. It's a really inaccessible location.

View attachment 190040 View attachment 190039

View attachment 190038 View attachment 190037

I removed that red relay on the right and the pump went on working without it. So, as my brother pointed it out, I looked at the schematic on inner side of the relay box cover and there it states that red relay controls the heater fan.

View attachment 190041

Here http://fusesdiagram.com/fiat/fuses-and-relay-fiat-punto-2.html it states that the fuel pump relay is a black relay on the left side, however I don't have that one. So I'm assuming that's meant for diesel engines.

I also rechecked that ground connection (post#22,) it appears to be quite tight and I can't measure any voltage drop on it.

Hmmm.

All I know is I have a 2004 mk2B punto 16V and your car is nothing like I ever seen before.

We need some pictures of this beast I think

mkey · Apr 20, 2018

You mean a picture of the car's body? It's almost exactly the same as this one.

And some actual pictures.

judderbar · Apr 20, 2018

sorry i got that relay wrong. you dont have t10 so you want relay t09 which is the red relay nearest the headlight.

mkey · Apr 20, 2018

judderbar said:
sorry i got that relay wrong. you dont have t10 so you want relay t09 which is the red relay nearest the headlight.

OK, no problem, I'll check it out tomorrow. I just wanted to add that, practically the only way to start the engine is to directly crank it, if I keep the key in ignition things go sideways.

Panda IIs · Apr 20, 2018

Hi

I've been following your trials with interest and will add my two cents. I've not owned a Punto but a series of other Italian "masterpieces" and I think its fair to say electrical problems are not unknown!

So first up that plate with the earths on looks unpleasant to say the least! I'd clean that up and look hard at the crimping to the eyelet.

With respect to the impact (fuel cut off) switch an earlier post suggested it would be by the glove box i.e. on the passenger side but this may be with reference to a right hand drive car. Left hand drive may still have the switch on the lefthand side i.e. the drivers side - have a look down by the sill area. On my Alfa 147 there was a discrete little plastic cover but i'd be very surprised this is the issue given the symptoms.

Did you try charging the battery overnight to eliminate any chance of low volts?

I admire your patience!

portland_bill · Apr 20, 2018

mkey said:
OK, I found the ECU,

If you have found the ECU, the pics you've posted are not it. The pics you've shown are of the throttle body. (The electronic equivalent of a carburettor) A few sensors and actuators there, but no ECU.

Look back at post #28 .
Top right of the four pics is pointing at the ignition ECU. You have one like that somewhere. Then follow the wiring to locate the single earth terminal and check it is clean and secure.
The bottom right of the four pics is a good overview of the engine bay. Let's have a look at yours please.

The intermittent nature of the problem is either a bad connection, probably an earth, or a worn ignition switch.
You've found the ignition switch, you could try disconnecting that, and joining the relevant wires together to put ignition on, and start function. (You'll need a wiring diagram). That would make known good connections, and prove whether the actual ignition switch has poor contacts inside. You will need the key in the ignition switch to be read by the immobiliser, and to unlock the steering.

mkey · Apr 21, 2018

Panda IIs said:
On my Alfa 147

They say you buy an Alfa once and for all, because you won't ever be able to sell it.

Panda IIs said:
Did you try charging the battery overnight to eliminate any chance of low volts?

I didn't but I did measure the voltages and they looked OK. I'll retry measurements in the morning, after the car has been idle for a while.

mkey · Apr 21, 2018

portland_bill said:
The bottom right of the four pics is a good overview of the engine bay. Let's have a look at yours please.

Will do.

portland_bill said:
You've found the ignition switch, you could try disconnecting that, and joining the relevant wires together to put ignition on, and start function. (You'll need a wiring diagram).

Can this be used reliably? Further, how certain can I be that the immobilizer is working correctly?

http://fiat-punto-cars.info/electrical-systems/210-wiring-diagrams

mkey · Apr 21, 2018

Here are some shots.

Panda IIs · Apr 22, 2018

mkey said:
They say you buy an Alfa once and for all, because you won't ever be able to sell it.

Mmm; well my '82 sud sprint shed its body when it had too many holes in it and became a Minari Sprint and, you guessed it I still have it lol

The GTV V6 was sold and at a profit - fabulous car and still miss it

the 2002 147 was my first ever new car and was run for 15 years - it comitted suicide by popping out the crankshaft seal on a roundabout pulling a few g's lol (worn thrust bearings).

I didn't but I did measure the voltages and they looked OK. I'll retry measurements in the morning, after the car has been idle for a while.

My point about charging the battery is that without a load you will likely get decent voltages with a digital meter but once cranking voltages are applied these can plummet. Good luck

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