Thread: Wierd Electrical Issues - Technical Help Required

Originally Posted by Mk1_Oz

Calling out to all the technically minded.......

The son's 2003 D2 HSE is having a major dummy spit that I have not yet been able to locate the source of. Symptoms below;

1. Radio stopped working (Son took it to auto lecky who replaced the auxillary battery isolator saying it was stuffed. Radio comes off aux. battery. Radio then worked)
2. Alarm started sounding during the middle of the night. Dash lit up like a Christmas tree (all lights on including flashing green S&M). Car could not be moved (no power). Son eventually disconnected batteries so they could sleep

I took a look this morning and found;

1. Connected batteries. Dash lit up like Christmas tree (all lights). Clicking from a relay in under bonnet fuse panel (think it was the black engine relay or the black 'book' icon one next to it). Car would not start (nothing happened when turning the key). The dash 'P' park indicator was flashing some onscure character. Both batteries showing around 11.9 volts.
2. disconnected ONLY the aux. battery. Dash appeared OK. Car started ok. Main battery showing 14+ volts.
3. Put Nanocom on car to look at fault codes. Initially had a lot of trouble getting it to read the modules especially the gearbox. Eventually got it and found no codes to alarm me.
4. Car would then not stop running when the key was turned to off. It continued for 1/2-1 minute then eventually decided of its own accord to stop.
5. Much checking for wire and earth connections followed but nothing untoward found
6. I then pulled the engine computer out (2 large connectors - 1 orange 1 black) and found a thick coating of dirty black oil inside one end of the orange connector. I used some contact cleaner spray to clean out the connectors (very dirty) then plugged it back it. Car started OK and stopped OK. Left aux battery disconnected.
7. Test drove OK but no indicators unless the lights were on and also the 'P' park symbol came back once lights were on too!
8. Door locks no longer responding to the key fob although the red flashing LED on the dash does.
9. Dash lit up like a Christmas tree again.
10. Disconnected all batteries. Kicked a tyre and came in for a cuppa before going to work. grrrrrr

Anytime there are strange occurances on a car, the best bet is always to check earths first. I checked teh ones I could see and wanted to specifically check the engine computer earths but I could not work out which were teh earths from the RAVE diagrams.

I had suspected that the auxillary battery was dead and was the cause of the faults (low volts do strnage things sometimes) but that wasn't it. I also had a thought that maybe in replacing the battery isolator that the leck spiked the computer and fried it. Seems doubtful.

Can those in the know suggest a course of action? I think I need to go over every earth and check them which means finding where they all are especially the computer ones. A multimeter between the earth point and the battery negative will show up any faulty earths. I do not know how to go about checking the computer seeing as there are not any specific faults. Does the D2 use a CANBUS?

I hate parts changing as a method of fault finding even though the computer is one of my suspicions.

Me id be isolating the dual battery set up incl what the sparky did as it seems like where it all started might be a little obvious
So yes separate the aux battery and islolator

Just a D1 owner here, but could Number 6 be a clue? Oil in the injector loom getting into the ECU is quite a well documented issue, is it not?

Has the car had "oil in the loom" problems before?

If its a TD5 pull the plug off the front corner of the head and see if any oil runs out at that end.

14v on the main battery- was that running or off , seems very high if off , could be worth testing the voltage running and see if a faulty reg on the Alt is putting high voltage thru the ECU.


My TD5 had issue's once where the alarm went off and couldn't be stopped unless the battery was disconnected and it was a bad battery , had a couple of bad cells , caused lots of issues,


Start with the very basics , even try a different battery if you have 1 available , and disconnect any dual battery system and turn off the radio , uhf etc and go from there.


Just my 2c worth.

Cheers Ean

14v was running so all good.

I cleaned the ecu connector of oil and things improved. I will check the injector loom connector also.

I plan on taking both batteries to be tested tomorrow as i agree that a dud battery can cause strangeness.

Thinking more about the symptoms, the son reported no power when he was playing around. Given the green s&m lights were on i suspect the trans had gone into limp home mode.

TD5 btw...

Hi, the oil in the engine ECU plug can cause running/starting issues only nothing else, +1 to isolate that dual battery setup cos IMO that's the cause for the other problems, as long as the voltage to the systems(on the engine bay fusebox's main feed) is below 12v all kind of oddities can occur... though if after that it still makes tricks go for te alternator cos a problem in it's circuit can cause that symptom with the non stopiing engine with ignition off

Originally Posted by Mk1_Oz

Calling out to all the technically minded.......

The son's 2003 D2 HSE is having a major dummy spit that I have not yet been able to locate the source of. Symptoms below;

1. Radio stopped working (Son took it to auto lecky who replaced the auxillary battery isolator saying it was stuffed. Radio comes off aux. battery. Radio then worked)
2. Alarm started sounding during the middle of the night. Dash lit up like a Christmas tree (all lights on including flashing green S&M). Car could not be moved (no power). Son eventually disconnected batteries so they could sleep

I took a look this morning and found;

1. Connected batteries. Dash lit up like Christmas tree (all lights). Clicking from a relay in under bonnet fuse panel (think it was the black engine relay or the black 'book' icon one next to it). Car would not start (nothing happened when turning the key). The dash 'P' park indicator was flashing some onscure character. Both batteries showing around 11.9 volts.
2. disconnected ONLY the aux. battery. Dash appeared OK. Car started ok. Main battery showing 14+ volts.
3. Put Nanocom on car to look at fault codes. Initially had a lot of trouble getting it to read the modules especially the gearbox. Eventually got it and found no codes to alarm me.
4. Car would then not stop running when the key was turned to off. It continued for 1/2-1 minute then eventually decided of its own accord to stop.
5. Much checking for wire and earth connections followed but nothing untoward found
6. Test drove OK but no indicators unless the lights were on and also the 'P' park symbol came back once lights were on too!
7. Door locks no longer responding to the key fob although the red flashing LED on the dash does.
8. Dash lit up like a Christmas tree again.
9. Disconnected all batteries. Kicked a tyre and came in for a cuppa before going to work. grrrrrr

I reckon the auto sparky has connected a live to a switched earth somewhere. The car not turning off sounds very much like the ignition staying live for a period of time... like maybe a radio timeout or perhaps the VSR timeout keeping the voltage path high?
The radio will probably have 3 live connections to it, +ve all the time for memory, +ve with ACC to tell it to go on and +ve with lights to activate the dimmer. If he has the second battery running the radio then I can't help but think the +ve rails are being bridged somewhere with the radio.
The oil in loom won't cause many of these issues.
No 4 and 6 just sound like someone has mistaken a non-live live for a ground.
I borrowed a mates car once that kept blowing the fuses for one side, couldn't figure it out until I realized he'd used the +ve light signal for ground on the radio, no radio on and lights ok, radio on and no lights OK, lights and radio and plink goes the fuse IIRC, radio kept working too .

What you say makes sense and is similar to the path I plan on taking.

Batteries were checked this morning and all OK although the main was a little down on charge. Got it on the CTek now.

Just sat here looking at the wiring diagrams to ID the earths then back to the cold cold shed.......