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Bodged wireing now car won’t start


Keith Cooper
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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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Another thought you could try is whilst turning over the engine have somebody spray some easystart into the throttle body, if it tries to fire/run then you know you have spark & it's just fuel you're lacking. You could also take out a plug to check obviously, but I'm lazy

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50 minutes ago, Longboarder said:

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?

This is an interesting point.   I initially assumed it was something to do with the rev counter, but when I got a spare instrument cluster I drew up a diagram for the printed circuit board on the back.   At first check that pin does not appear to be connected to anything on the cluster.   That doesn't make much sense (although this a Robin Hood we are talking about 😀).    I didn't follow it up (if it ain't broke don't fix it), maybe I should.

Because the Fuel pump doesn't run when the ignition is switched on I still think the problem lies with either the Fuel Relay (I had one fail on me), or the ECU Relay.    As I said before, if you can hear the stepper motor operating and the ECU relay switching off 10 seconds after the ignition is switched off then the problem is the Fuel Relay If not then it is the ECU relay.  And swapping each one with the Horn Relay (which is what I did), will solve the problem.

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Red herring. Probably to the rev counter as you say.

Another thought. Do you get warning lights on the dash? All there? Oil light goes out when cranking? Rev counter registers?

Disconnect 18 anyway in case its blown through to earth via the rev counter. (Thinking: when you wrong plugged it something in the dash got 12V it wasn't expecting or able to cope with. Hence the spark.)

Did you wrong plug when the ignition was on ( If so the spark might be unimportant or very important.) or did you get a spark when you switched ignition on after (in which case the spark is vital)?

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Cable in the post.  Once installed you will be able to test the 2 relays using software.   Not sure if you know already but the data port is a floating 3-pin plug near the ECU with a rubber cap.

Edited by alanrichey
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Hi guys, I definitely have no spark, I have taken out the plug and checked, also I have no power going to the coil, I have put a multimeter on it and it has no power, there is a fuse below the coil and I have checked that but there is no power going to the fuse.. this is a bright green wire that appears to be going to the ECU.... it’s gets very difficult to see because it then goes behind the dash and visibility is very poor..., I may have to take out the dash.... 

all the indicators and lights work.... but I have no ignition lights at all.... the car does turn over just doesn’t start 

I'm convinced there is either a fuse I can’t find or the ECU has gone.... I have a friend popping over tonight who is a lorry mechanic so another pair of eyes may help

What is strange is when the multi-plug came out of the back of the clocks, the car would not start, when I pushed it back the car started and this happened a few times, I was going to work out a more secure way of fixing them in when I put them in upside down and got the spark.... it doesn’t spark anymore which is why I think something has blown...

Very confusing 

 

 

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Hi guys.... I think I have made some progress:

i ran a live wire directly from the battery to the live side of the coil and he presto I suddenly heard the whirring noise from the fuel pump... so I held the wire on the positive side and got my wife to start the car.... and believe it or not it started up perfectly ....

when she turned off the ignition the car continued to run until I disconnected the live I had put on the coil .... is it possible that somehow the ignition live on this car has been wired through the dash ?, very strange but at least I am getting somewhere .... 

any thoughts ???

Regard Keith 

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I did a search for the Escort Mk7 instrument cluster and it suggested that Pin 18 is an ignition switched live (output).    So I guess that makes sense if that is the primary source of power to the coil.  It also explains why I couldn't find it linking to anything as it probably connects internally to the 12V ignition input to the cluster.   You have probably burnt out part of the circuit board.   You just have to find the gap and solder a jump wire.

Or, if you can't find what has burned out all you need is an alternative source of ignition-switched live and join that to the coil.

Edited by alanrichey
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Hi Alan, yes I think that makes sense, I think I will be better off wireing a new wire from the ignition to the coil via a new relay, that way the dash clocks will have no effect on my wireing.

i have found a replacement set of clocks from eBay for £18, so I have ordered it to see if that makes a difference, I’ll let you know how I get on

I'm certainly learning a lot more about the Robin Hood a bit more quickly than I had planned :) 

 

best Regards  

keith way 

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Looking at your wiring diagram, no power to the coil also means no power to pin 2 on your ECU and no power to pin 20 on your dash as both those are fed from the coil positive. So you have a break between battery pos terminal and the coil positive terminal.

Prove the segments of this circuit a bit at a time.

Is there continuity between batt pos term and ign switch pin 1. Looking for wire failure or blown fuse between these points.

Is there continuity through the ignition switch to pin 4 when the key is turned on. (Could be a failure of the ignition switch).

Is there continuity from ign switch pin4 to coil pos. This last only if the wire goes direct from pin 4 to coil pos. Sometimes a builder and most manufacturers put a whopping (say 80amp) relay in, operated by the output of pin 4 to supply all the ignition live circuits (which would include dash, coil, ECU, wipers, heater,etc) so the green wire to the coil may not come direct from pin4 but may instead come from pin 87 on a hidden heavyweight relay.

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