Power to lnjector loom

Hi there my 2001 1.4 Tdi won't start. I fitted a new injector loom and new fuel filter still nothing so put a meter on the 4 connections on the plug that goes onto injector loom with the ignition on and getting no reading then cranked it over and still getting no reading is this normal or do I have an ECU problem
 
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J66RRY said:
Hi there my 2001 1.4 Tdi won't start. I fitted a new injector loom and new fuel filter still nothing so put a meter on the 4 connections on the plug that goes onto injector loom with the ignition on and getting no reading then cranked it over and still getting no reading is this normal or do I have an ECU problem
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Hi J66RRY,
Is the plug fully home & the locking ring fully rotated , I had this recently.
Hope that helps you
Keith.
 
That depends on how you were checking the loom plug. Of the 4 connections 3 will be positive and the fourth a common earth. So would only expect to see voltage between each injector positive and the common earth as that injector is instructed to open.

Earth being the brown wire and red injector one, yellow injector two and white injector three.
 
Any previous issues with the engine suddenly dying before the loom change, especially when the engine was hot.

Just thinking a failing crankshaft speed sensor will stop the engine, and presumably cut the signal to the ECU and injectors even when cranking

Cheers Spike
 
spike said:
Any previous issues with the engine suddenly dying before the loom change, especially when the engine was hot.

Just thinking a failing crankshaft speed sensor will stop the engine, and presumably cut the signal to the ECU and injectors even when cranking

Cheers Spike
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My thoughts exactly, Spike.
 
Thanks for the replies when testing the 4 connections I was just putting a meter on each connection and an earth then cranking engine and getting nothing. Also the day before the engine failed to start it started losing all power under anything over 20% acceleration and strangely the next day battery was dead? After charging it behaving fine now. So would a failed crankshaft speed sensor cause no power to injector loom
 
Well your testing of the injector loom plug was wrong. The ECU provides the positive AND earth connection so testing to another earth proves nothing.
 
OK eventually got round to checking power to injector loom with ignition on and also while cranking only getting a reading of 0.08 volts on all 3 connections to the common brown earth also just noticed today that rev counter not moving while cranking (crankshaft speed sensor faulty)?
 
J66RRY said:
OK eventually got round to checking power to injector loom with ignition on and also while cranking only getting a reading of 0.08 volts on all 3 connections to the common brown earth also just noticed today that rev counter not moving while cranking (crankshaft speed sensor faulty)?
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Yes, crankshaft sensor most likely if no rev counter movement.

Mac.
 
100% agree. If Rev counter not registering cranking engine speed then crank sensor as failed

Ecu does not register crank rotating =. Ecu not telling injectors to open because it does not know when to open close each injector

Access is jot great to the crank sensor. Remove the oil cooler to gain access
Took me about an hour to change the last one

Paul


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Mine was done just before I bought the car and guess what was leaking? Yes the oil cooler seals, so taken care with those or replace. Some.delicate items down there like the oil filler pipe to block ...
 
Ok conclusion is that its the crankshaft speed sensor so before buying one and the hassle of fitting I decided to get a second option. Two hours later AA man arrives connects laptop and confirms no signal from CSS so checks under bonnet and as soon as he touches plug from wiring loom to plug to CSS one of the wires breaks in two (think it was the blue one) so soldiers a wire in to restore connection and it started first Time 😁😁😁so CSS diagnostic correct but it was actually the broken wire and not the actual part Happy days
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Excellent news and a cheap fix

Diagnosing from symptoms alone is always likely to mis things like this which would have been eyeballed if actually looking at the car being diagnosed
Good to see that we were on the right track

And thanks for reporting back the findings

Cheers Paul


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