ECU wiring loose connection - Alfa Romeo Forum
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(Post Link) post #1 of 10 Old 05-07-16 Thread Starter
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ECU wiring loose connection

I have been having problems with my 2007 2.4 JTDM 159. Every now and then I loose the injector on cylinder 1 and VDC, Hill holder etc and she runs lumpy (because only on four cylinders).

I found the culprit, or rather where the problem is, it is the loom connected to the top half of the Engine ECU. see the video in the link, you can see with minimal movement the problem can be created and solved.

I would obviously like to fix it but I am nervous of dismantling the plug incase i loose the pins proper locations.

Has anyone had this problem before? is it common? and is it the plug or an exposed wire further up due to vibrations?

Ah ********! - apologies for vertical record fail

https://www.youtube.com/watch?v=gBTRKUlKJqE
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Might be worth trimming open the trunking to expose the wiring as it might reveal a break or chaffed wire which can easily be fixed?
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(Post Link) post #3 of 10 Old 08-07-16 Thread Starter
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Thanks I'm having a look now, no obvious shorts or connection breaks :/
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Pop the connector out (disconnect the battery first) and check pins for signs of corrsion. If you have some contact cleaner give them a blast. I've had this commonly on motorbikes where connections corrode, sometime in the connector block itself which creates voltage resistance.
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Right, if I apply pressure to the body of the plug and hold it against the ecu, I can move the wires in all directions with no effect. So to me that means the connection fault lies between the plug and the the pins in the ecu? . I have used electrical contact cleaner but the fault can still be induced.. any ideas?
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Thanks smokey, the pins and the plug look fine, no signs of corrosion
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Well I managed to get the cap off the plug, everything was sticky from old insulation tape but again no obvious issues.

For a while I was fidling with the exposed wires while the engine was running and was unable to replicate the issue. It turned out the plug was not fully seated in the ecu so it is definitely a problem between the plug and ecu pins... I guess this is the kind of thing where a dealer would say new ecu required.
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Sounds like a fault in the connection block. To prove the theory, wrap a couple of cable ties tightly around the connector (drawing the connector and the ECU together). If all runs well then it solves the problem for now until you can find a more permanent solution.
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Quote:
Originally Posted by OldSmokey159 View Post
Sounds like a fault in the connection block. To prove the theory, wrap a couple of cable ties tightly around the connector (drawing the connector and the ECU together). If all runs well then it solves the problem for now until you can find a more permanent solution.
This i have done.. I'm going up north tomorrow some 150 miles, it will be a good shakedown. at least i know where the issue is. i have no idea how i will find a more permanent solution. unless i find another plug and solder each individual wire onto the new plugs existing wires. i tried for quite a while and was unable to gain access to the individual connectors inside the plug... i just hate messy in-wire solder joints.
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(Post Link) post #10 of 10 Old 28-08-16 Thread Starter
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This problem has reared its ugly head again so i managed to borrow a set of connector tools to remove the pins (i dont know the proper terminology for the tool kit) which worked very well and i was able to remove the entire plug casing revealing access to all the individual wires right down to their crimp connection. i could also remove the pins individually from the internal connector block.

Upon gaining all this lovely access i plugged the wires back into the ECU with the main plug casing still removed, my hope being that i could fiddle with each individual wire with the engine running until i find the one with the problem. However, no matter how i manipulate the wires i could not then get the problem to re-occur.

thinking that one of the wires i pulled out and looked at must have not been seated correctly to start with i patted myself on the back and put the plug back together, cleared the error code and started her up!.....

Problem is now back! after alot of expletives i again pull the plug apart and reconnect without the main housing and again i cannot replicate the fault so i'm stumped and have left it as is but there is nothing to secure the pugs in place so they'll likely fall out soon.

I'm not a thick person and have always been quite good with this sort of thing but this has beaten me good and proper, i sat on the front cross member laughing at it in disbelief....

The only thing i can think of now is this: the mate i borrowed the tools from said 'when you find the break, make sure you use a crimp connection to fix it because solder will give a different resistance and may cause problems with the canbus signals' fine i thought, i will. thinking about it now, the replaced connector on the Cyl 1 injector has been soldered on so it could be that by fiddling with the ecu plug the canbus isn't happy depending on the resistance in the plug terminals which may compensate for the soldered plug if squeezed on tighter? i don't know.

i'm almost at the point now of paying an auto electrician to have a look. i suppose i should re-do the injector connector first.
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