Technical The mystery of the relays - 1.2 8v

[boguing]

Problem 1 = Fuel pump relay is dead.

Problem 2 = Everything I've managed to find (box lid/web/posts on here usually) says that the fuel pump relay should be in the gap between the two reds on the left. (T10)

(Picture nicked from @Ziggy122)

Like him, I don't have anything in T10.

If anyone knows which one the fuel pump is actually switched by I'd love to know.

This is in the car I gave my daughter and two new relays (one red, one black) are on their way to her. Rather than get her to swap each one in turn it would be nice if I could tell her which one to replace.

Thanks.

 

[boguing]

Oh, a supplementary question!

The car refused to start a couple of weeks ago, today was the first time I was able to go up to her place to sort it and I suspected the relay might be the culprit. Hooked up the laptop and it confirmed it. (A small victory).

I did try swapping the fuse bottom left which the web says is the ECU one (but the lid shows an injector, so dunno) and the car still wouldn't start. I could have continued swapping but it was dark and I was hungry.

The question that just occurred is - will I need to clear the fault after finding the right hole for the new relay?

 

[judderbar]

Oh, a supplementary question!

The car refused to start a couple of weeks ago, today was the first time I was able to go up to her place to sort it and I suspected the relay might be the culprit. Hooked up the laptop and it confirmed it. (A small victory).

I did try swapping the fuse bottom left which the web says is the ECU one (but the lid shows an injector, so dunno) and the car still wouldn't start. I could have continued swapping but it was dark and I was hungry.

The question that just occurred is - will I need to clear the fault after finding the right hole for the new relay?

you dont need to clear faults. and after 3 starts with the fault corrected and with a running time of a few minutes the engine light turns off while the fault code remains stored and creating no driving difficulties

 

[boguing]

you dont need to clear faults. and after 3 starts with the fault corrected and with a running time of a few minutes the engine light turns off while the fault code remains stored and creating no driving difficulties

Ah, that's good news - she should just be able to bung the relay in and go. If it had needed clearing it would have meant going back up and getting another free dinner. Oh, wait...

 

[boguing]

Ok, the relays arrived and The Daughter has swapped pairs in turn. Still won't start.

A week and a half ago MES said 'fuel relay' dead, which is what I had guessed so was quite happy. With that I unplugged and came home. Maybe I should have looked a little deeper.

Anyone know if a dead fuel pump would report as a relay failure? Guess it could also be a bit of corrosion in the relay socket.

ps. Car in SE London, me in Dorking so gearing up for a Sunday visit.

 

[crankshaft]

Anyone know if a dead fuel pump would report as a relay failure? Guess it could also be a bit of corrosion in the relay socket.

I don't think it would. There is an isolation between the control side and the load side of the relay. That error from MES points out to a problem in the control side.
If you have a new relay, the problem could be the corrosion you mentioned, or in the wires going from the relay socket to the ECU.

 

[boguing]

I don't think it would. There is an isolation between the control side and the load side of the relay. That error from MES points out to a problem in the control side.
If you have a new relay, the problem could be the corrosion you mentioned, or in the wires going from the relay socket to the ECU.

This is why I'm so peed off with Haynes. I'm currently having an email row with them about leaving out all the wiring diagrams for ignition and fuel, as well as not identifying any of the relays. I was gobsmacked to be told that it was sometimes necessary to leave bits out to save space!

They've sent me some more information but half of it's wrong, telling me that if I buy the digital version it's all in there. Now we're haggling on the price.

 

[boguing]

Ok, story goes on. For various reasons I couldn't use mes, but now that I have, it still sees the P0230 fuel relay fault and P0115 water temp sensor fault. Cleared them, restarted still there.

Knowing that there's nothing wrong with the relay it really has to be the wires to pins B6 and B17 to the LHS ECU plug - doesn't it?

So if there's a wiring problem on one plug, which is more likely, a water temp sensor fail, or one of its wires to the ECU (A5,13,14 and 25) on the RHS plug?

Edit to add. The water temp gauge works perfectly.

 

[The Panda Nut]

This is why I'm so peed off with Haynes. I'm currently having an email row with them about leaving out all the wiring diagrams for ignition and fuel, as well as not identifying any of the relays. I was gobsmacked to be told that it was sometimes necessary to leave bits out to save space!

They've sent me some more information but half of it's wrong, telling me that if I buy the digital version it's all in there. Now we're haggling on the price.

Haynes refunded me. I told them they should be ashamed of degrading the old brand.
Bear in mind some codes have more than one trigger. I tend only to use as vague indicators. Then when they are pinpoint I smile.

 

[judderbar]

The first thing is to understand the code

P0230 Fuel Pump Primary (Control) Circuit Malfunction

Detailed information on troubleshooting and repairing a P0230 DTC code which has to do with a fuel pump primary circuit malfunction. Also includes links to relevant forum topics on the code.

www.obd-codes.com

The ECU is detecting there is an electrical circuit problem in the chain of connections from the positive pole of the battery via the fuse box through the coil of the relay and then back to the ECU via the earth wire which the ECU controls to operate the relay. All the ECU knows is when it tests that chain of connections it is not testing correctly. The code is not a fuel pump relay failure code

 

[boguing]

Fixed.

On the underside of the engine compartment fuse/relay box there are about five connectors. I disconnected them all, sprayed each plug and socket with contact cleaner and then put them in/took them out four or five times to dislodge anything the contact cleaner was releasing. I did the same with the two on the back of the engine ECU. I also took off the main 12v supply to the fuses and cleaned it, but it was bright and shiny and unlikely to have been a problem.

Checked for faults with MES and fuel pump relay and water temp sender were logged as failed. Cleared them, started the car and checked again. All fine. Previously the fault came back without even running the engine. It now starts like it used to, almost before you turn the key!