Technical Car Security Failure: Loose Connection

[aijosh]

Ok. I've gone through the forum and also based on my little experience I see I have a long list of tasks for me.

I'm posting anyway just in case I can get stirred in the right direction and avoid the 1 million trials I might need to do in order to trace the issue.

SYMPTOMS Progression:

A. Engine stalls if a very quick deceleration is executed from high speed. (No error codes stored) This has been happening for a while.

B. Engine stalls for no reason (No error codes stored)


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CURRENT
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C. Now car wouldn't start. Cranks ok.
[[When Key is on, Car Security Padlock Blinks 3 times and stays on]]
[[Car Security Failure: Loose Connection displays on dashboard screen]]
[[OBD II reader doesn't connect to ECU so I cannot read code]]

D. After fiddling with wiring between Fuse Box and ECU (mostly just tugging and wiggling, including the fuses and relays) car starts up.

No check engine light but I read stored stored codes

E. Error Codes read

P0335
U1600
U1601
P0606
P0443

F. Clear error codes

G. Start engine again and works ok for some minutes then stalls.
Loose connection.

Back to C.

Then D.

H. After D. Car stalls again. Cranks but wont start.
This time error code P0443
I pulled the fuel line close to the engine and notice fuel not supplying when key is on.

Anyways,

Back to D.

Then G.

Then C.


SUMMARY
I'm struggling between C., G. and H.

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From what I gathered from the forum, I have a long list of tasks to do.

Any tips on where to start (what to do first) is welcome.



PS: At some point while troubleshooting, the Throttle body just started clicking continuously when the key is on. I had to disconnect one of the relays on the fusebox then reconnect it to stop the behaviour

 

[flyingdutch]

Is it a 1.6?

 

[aijosh]

Is it a 1.6?

Yes.

1.6 16V 5door

 

[flyingdutch]

Did you check the ecu pins?

 

[aijosh]

Did you check the ecu pins?

Yes. 3 of them are slightly lower than the rest. 55,56,57
Do I need to resolder them ? Not sure I could successfully do this. I've never been good at soldering circuit boards.

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UPDATE
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I was able to sort of change the problem behaviour.

I noticed the fusebox had separated causing a handful of the fuses to just hang in the air without being connected to the pins inside the fusebox OR just barely touching the pins.

I glued the fusebox shut at the open end (though it still didn't hold. After reinserting the fuses and relay it separated again). But I was able to get it to stay together and the fuses now seat properly in their terminals.

So I'm no more going round in circles of C., G. and H for now and only C. Car Security Failure: Loose Connection is persistent. But with a new twist

If touch anything, relay, fuse, wire (or maybe its if I wait long enough) and go back to switch the key on the padlock disappears BUT once I start it cranks and doesn't then on second attempt padlock comes back.

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Final observation
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If it wait of go wiggle stuff key turns on ok (no Loose connection) BUT any attempt to connect the OBD II reader would trigger the Loose connection error and the reader would not connect.

Also I noticed if I key on the first time: No padlock
Then instead of cranking the engine, if I switch off and key on again, Padlock appears steadily.
If I do this the third time, padlock blinks 3 times and stays on.

So the first key on seems to just be a facade. Any attempt to start the engine turns out fruitless. Just cranks.

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What I do now is just cycle the key on and off 2 or three times to see if the padlock comes on which it always does now. Engine doesn't start.

The only issues I've been getting repeatedly now is

.1 the relay T09 keep acting up. Most times is clicks continuously when I switch the key on. I have swapped it with every other relay and same behaviour.
.2 Other times the throttle body clicks erratically for about 2 secs when I switch the key on then stops.
.3 First key on, no padlock, second key on, padlock issue begins.

 

[aijosh]

Fusebox vs ECU

I'm probably going to be faced with the option of changing my ECU.

I just want to eliminate all other options available which includes changing the fusebox but a mechanic here is telling me changing the fusebox would need the car to be reprogrammed.

Is this correct?

Also would changing the ECU need the car to be reprogrammed?

I'll probably start with the one that doesnt need reprogramming.

 

[flyingdutch]

Re: Fusebox vs ECU

No changing fuse box under the hood doesn't need programming, it only needs programming if you change out fuse box under the dash.
I would change the fuse box under the hood and resolder ecu pins for a start

 

[aijosh]

Re: Fusebox vs ECU

Ok. Thanks.

I'll do those and post an update in the thread with main issue.

 

[Davren]

Re: Fusebox vs ECU

No changing fuse box under the hood doesn't need programming, it only needs programming if you change out fuse box under the dash.
I would change the fuse box under the hood and resolder ecu pins for a start

It would only need programming if the body computer was changed. The body computer can be separated from the dashboard fuse box and fitted to a replacement fuse box, so would not need programming in this scenario.
.

 

[TheWeathers]

I had very similar problem to yours - Loose Connection while delecerating or braking and changing gears. I fiddled with ECU, D4 connectors and all the wiring for the whole day but in the end it came out that the crankshaft position sensor was faulty and replacing it solved all my problems. I don't know if you find it useful because my powerplant is 2.4 petrol engine.
For the first few times I also thought that fiddling with fuse box and wiring helped but soon after I realised that I could start the car without touching the wiring after a 5-10min cooldown but right after I started driving it could cut me off after a 500 meters drive.

 

[aijosh]

or the whole day but in the end it came out that the crankshaft position sensor was faulty and replacing it solved all my problems. I don't know if you find it useful because my powerplant is 2.4 petrol engine.
For the first few times I also thought that fiddling with fuse box and wiring helped but soon after I realised that I could start the car

Yes. You are absolutely correct. I was suspecting this and swapped the crankshaft sensor with another one from the junkyard and the car is back up and running.

I actually did have a fusebox issue as I stated in the second to the last post I wrote.
The P0443 was because the fuse to the fuel pump was partially making contact due to a separated fusebox. (See attached image.) I stopped getting the fuel supply issue once i sorted the gap out.

Thanks to everyone for their input. They are really appreciated.