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Bodged wireing now car won’t start


Keith Cooper

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Hi, I have the super spec with Rover engine, it has what looks like ford Puma clocks and behind the clocks are two multi plugs into the clocks, whilst changing the stereo the plugs came out and at first I didn’t notice until I went to start the car, it wouldn’t start... I realised the plug had come out and plugged it back in.. the car started fine, the next day I went to Finish putting the stereo in so Double checked the plugs in the back of other clocks and because someone has modified the plug it was possible to put it in the wrong way round.... which unfortunately I did, there was a small spark as I put the plug in so I knew straight away the plug was upside down, but now the car will not start it just turns over.

i have checked every fuse I can and all is ok , I can’t get to the ECU very easily , before I call a auto electrician in

is there a fuse in the ECU I could have blown?

is there anything obvious that I have missed ?

 

thankyou 

Keith 

 

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No there isn’t a fuse in the ECU but the ECU is powered by a relay with a fused supply. You can check if the ECU is working as it also turns on the fuel pump via another relay. When you turn on the ignition can you hear the fuel pump prime for a couple of seconds? If not, then there must be a blown fuse somewhere.

I’ve got a wiring diagram for the two plugs into the back of the Escort instrument panel, but I’m not at home atm. Have to sort them later for you. 

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Yes I have found all three relays, and there is a small bank of fuses next to two of the relays and they all ok... the fuel relay has a fuse on its its own and that seems ok as well... unless there is another fuse somewhere else under the dashboard I can’t see.

the problem is definitely electronic because the car turns over but no spark to the plug, also no fuel pump noise when you first turn on the ignition. .... I know I’m missing something I just don’t know what ?

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That's a bit odd.  I actually took my car to a Show without any dashboard or any of the instruments.  I just labelled it "Under Construction".😀   I can't think of anything in the cluster that would prevent it starting (depending on how it's been modified)

As Andy said, the first thing is to listen to the fuel pump to see if it runs for 2 seconds when you switch the ignition on.  As you don't hear anything that probably means that the power to either the ECU relay of the Fuel Pump relay has gone.   The second thing to do is listen very carefully when you turn the ignition off.   You should hear a series of clicks as the idle stepper motor returns it to start position and after about 10 seconds a definite click as the power is removed from the ECU relay  (The ECU remains powered up for a few seconds after the ignition is turned off, to allow a bit of housekeeping.

And try swapping the 2 relays with a known good one (I use the horn relay)

I'll get the diagnostic lead in the post as soon as I can as that should highlight the problem.

Edited by alanrichey
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Hi Alan, yes I thought so to but the wires or the instrument panel definitely stops the car starting, the wires behind the clocks look a bit of a mess really, I guess it’s wired that way... I will get a multimeter and test the wires to see if there’s any power going to them 

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One more thing - check if you have an in-line fuse somewhere around the coil. The original wiring on my car had two wires on the coil + terminal. One came out of the loom which I traced back to the white power cable from the ignition switch. The other had an in-line fuse and went to the instrument panel, joining to the white/black wire on terminal 12 of the black panel connector to feed the rev counter.

I don’t see how this would stop the ECU working though. 

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And as promised, this is the instrument panel wiring on my car. The wires in the Ford connectors were spliced to the Superspec loom as follows.

White connector:

1 orange/blue to red - 12v from lights for panel illumination

2 purple/white to blue/white - main beam

3 black to black - earth for illumination

4 empty

5 black/yellow to black/yellow - brake warning

6 white/green to blue/green - temp sender

7 white to green/black - fuel sender

8 black to black - earth for fuel & temp gauges

9 empty

10 empty

11 empty

12 purple to green - 12v switched power for gauges

Black or Blue connector:

1 black/red to black - earth for indicator warning

2 blue/yellow joined to green/red & green/white - indicator warning

3 empty

4 empty

5 empty

6 empty

7 blue to brown/yellow - alternator warning

8 black/green joined to both black - coil -ve  and also white/black - ECU pin 25

9 white/green to black - earth for tacho

10 black/yellow to white/brown - oil pressure sender

11 empty

12 white/black to green - coil +ve

Your wiring colours may be entirely different of course, but hope this helps track down your issue  

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I see you have a 'crash' switch in the circuit to isolate the fuel pump.  Might you have knocked it ?    It is a couple of inches long, with 2 wires going in one end and a rubber-covered push switch on the other end.   It's bottom left on my electric board, underneath the 2 relays,

Just in case 😀

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I hope it's just the impact switch but if not......

Could you make a list of what is working when you switch on ignition? Wipers, indicators, heater, dash warning lights, dash illumination, dash gauges, main and side lights, brake lights, etc? Absolutely everything you can think of.

Can you then go through the relays and coil with a multimeter or bulb to see if you have power to coil positive, 30 and 86 on the ECU relay and 30 and 8* on the fuel relay.

A what's it for question. The connection from coil negative to 18 on the instruments? Who puts anything other than a switching wire on a coil negative?? Can you take it off the coil neg and do something else with the wire from18 on the dash?

Edited by Longboarder
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