Greasenuts

Ok so just gonna chuck this out there,

Got a customers 52 plate 1.4 fiesta diesel in the workshop, (think its 52, maybe later), it was recovered to us as a nil start, all it would do is crank for 1 - 2 seconds then stop cranking.

So I chucked the scanner on it and got a handful of codes relating to low voltages at various sensors, cam sensor, crank sensor, fuel temp sensor etc. Then I noticed that everything affected seemed to be toward the driver side of the engine.

Cracked it, I thought, loom fault.

Using the cam sensor as an example I checked the voltage to it and found just 1.5v, (should be 5v according to my tech data), so I traced the wire back to the ECU and checked again there, hoping for the full 5v, but no, also 1.5v out of the ECU.

Bollox, I thought.

So a quick check confirmed the ECU had a 12v power supply.

Sent the ECU off to be checked and repaired but it came back as ok.

At this point we were deep into the post christmas rush so I didnt have a lot of time to put into this fiesta so I asked the local Auto Electrician to come and have a butcher, after a couple of hours he came up with exactly the same diagnosis as I did - faulty ECU, possibly can-bus related.

So, what now....

Well as it happens the gaffers been a bit scared by it and told the customer we dont want anything more to do with it, so its now out of my control. Fortunately the customer is very understanding, the car is still with us but he is going to arrange to get it back to his house.

Has anyone ever come across this before? It's just bugging me every time I look at it outside the workshop. I like to be able to finish every job I start.

Cheers for reading.

Mark

creator

So have you checked the can bus wires? These should add upto 5v when tested.test each wire to earth then add up the voltage from both.if thats what youve done and only have 1.5v theres a problem withthe bus system somewhere so youl need to trace the wires and see where else they go and to what other control units.

j6kyt

it could be the immobilser system.

Greasenuts

Erm, not that I'm aware of. Would they be the signal wires from the cam sensor back to the ECU? That would need a scope to test wouldn't it?

Thing is, I cant really put any more time into it now, I was kinda hoping for someone to say "ah yes, that will be the ........"

Greasenuts

Well our auto electrician was quite confident that the immobiliser was ok. (I've gotta say that he has a very good rep round our way).

What are you basing that on though?