"Interesting" electrical problem on ZR+ 2003 - MG-Rover.org Forums
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post #1 of 27 (permalink) Old 03-12-2016, 16:24 Thread Starter
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"Interesting" electrical problem on ZR+ 2003

Hi All,

I seem to have an electrical fault with this car...

At the moment, I've not been able to start it.

When I bought the car, it would start, either with a bump or...

To start the car, it seems I have to turn on the headlights and front fogs. If it doesn't start under these conditions, apparently, locking the car with the fob, waiting a minute and unlocking it sometimes helps.

Now I am thinking that the power or earth to some component (ECU/Immobilliser/Ignition) is interrupted and putting the lights in circuit is allowing the current to go to the affected component(s) via a different path from usual.

Anybody have any ideas or recognize this fault ?

I have the full Tech manual for the car, including all the circuit diagrams and so on, so I hope I can bottom this out as I need to get the car running.

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post #2 of 27 (permalink) Old 03-12-2016, 16:46
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If you have oval Pektron fob problem could be in water ingress on BCU connector. This problem is described very well in this thread by Technozen: Pektron SCU/BCU
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post #3 of 27 (permalink) Old 03-12-2016, 20:26
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You could start simple and try changing the battery in the fob, and check, clean and refit the earth strap on the spam panel.
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post #4 of 27 (permalink) Old 03-12-2016, 20:39 Thread Starter
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The fobs I have are rectangular. So it not the Pektron thing ? Or did i misunderstand that ?

Other symptoms are with the ignition in position II, that the clock doesn't display properly - very feint and a only few of the lcd elements show, again faintly and slowly flickering, the warning lights on the instruments come on but very weak, can only see them faintly at night, they can't be seen in the day. The hazards don't flash at the moment, but they have done previously. The indicators are not working either at the moment. But the rear and front fogs work as do the interior lights. The door windows work, but not the sunroof. The door mirrors work. When it was starting and I drove it, I noticed that the rev counter wasn't working and neither was the speedo.

I'm going to check all the fuses and relays tomorrow.

I may also disconnect all the connector blocks and use cleaning spray on them.
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post #5 of 27 (permalink) Old 04-12-2016, 01:21
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Spam panel? Yum yum

Apart from checking the security of the battery earth to inner wing and slam panel, check that the connections on the starter motor are tight and secure, and as far as possible check the underbonnet wiring for damage/short circuits.

I would also examine the tailgate loom where it passes from body to tailgate through the rubber boot at top right of the tailgate - chafed wiring here is a fairly frequent occurence and the resulting short circuits can cause a number of electrical malfunctions elsewhere.
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post #6 of 27 (permalink) Old 04-12-2016, 09:08
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When the slam panel earth failed on my wifes ZR it gave some very strange symptoms so I would start here. It actually finally went when she was in a car park warming the car up.

I would then do, as you are planning, unplug and replug all plugs, relays, connectors etc.

Also check for chaffed or damaged wiring at the hatch hinge, behind the radio and around the engines ECU.
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post #7 of 27 (permalink) Old 04-12-2016, 09:48 Thread Starter
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Thumbs up

I already took the earth strap between battery and the bolt on the gearbox near the starter motor and re-terminated the lug on the top end as the cores were freyed and dull, so i also cleaned the lug and the cores to shiny shiny shiny. I cleaned the lugs of the other two cables connected there and the screw and contact point with the body. Did that days ago.

I'll look at your other suggestions too. However, with a fully charged battery, the starter motor kicks round like a tazmanian devil... so no problem there. Although without the lights on, I don't even get the solenoid click.

Quote:
Originally Posted by Man in the Car View Post
Spam panel? Yum yum

Apart from checking the security of the battery earth to inner wing and slam panel, check that the connections on the starter motor are tight and secure, and as far as possible check the underbonnet wiring for damage/short circuits.

I would also examine the tailgate loom where it passes from body to tailgate through the rubber boot at top right of the tailgate - chafed wiring here is a fairly frequent occurence and the resulting short circuits can cause a number of electrical malfunctions elsewhere.

Last edited by quantumDavey; 04-12-2016 at 10:04.
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post #8 of 27 (permalink) Old 04-12-2016, 09:51 Thread Starter
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Yeah, the fobs work fine. I don't think they need new batteries. But I could replace them anyway, just to make sure. I take it the ID chip in the fobs is a passive (non powered) chip that is activated/powered by the ignition barrel transducer's magnetic field ?

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You could start simple and try changing the battery in the fob, and check, clean and refit the earth strap on the spam panel.
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post #9 of 27 (permalink) Old 04-12-2016, 10:03 Thread Starter
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Looks like I have a very busy day today, Guys.

Thanks for all your suggestions and help so far.

I'm determined not to let this beat me ! I don't want to call an auto-electrician out, but if anyone knows of any good but reasonable guys (preferably "free and for the hell of it" guys, lol) around the Stockport area... (I know... I'm just dreaming, there !!)

Evry body, needs somebody... somebody to fixtheircar... someone to fixtheirelectrics.... fella to fix... and so on... lol
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post #10 of 27 (permalink) Old 04-12-2016, 10:47
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Quote:
Originally Posted by quantumDavey View Post
Yeah, the fobs work fine. I don't think they need new batteries. But I could replace them anyway, just to make sure. I take it the ID chip in the fobs is a passive (non powered) chip that is activated/powered by the ignition barrel transducer's magnetic field ?
The fobs are powered by a CR2032 battery, and if the fob battery is weak it won't be able to transmit the signal for triggering the central locking.

The passive disarming of the immobiliser is done by the exciter ring around the ignition barrel which triggers the fob to transmit the signal to disarm the immobiliser. This will often still work even when the fob battery has become too weak to remotely operate the central locking. The passive disarming will not operate if the fob is not very close by the ignition barrel, and if it doesn't work you will normally just get a two-tone warning beep from the 5as unit behind the dash and the starter motor will not turn.

All your symptoms point to a short circuit somewhere, and the tailgate wiring loom is the probably the favourite, closely followed by the dash loom as mentioned by Talkingcars.

Good luck with finding the problem - these sort of issues can be a pain to find on occasions, but when you do find the problem, it is often fairly straightforward to fix
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post #11 of 27 (permalink) Old 04-12-2016, 14:40 Thread Starter
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Thanks again for all the info and encouragement. I'm sure I'll find it.

So, if the starter turns, then that means the immobiliser is re-mobilising the system okay ?

The locking and unlocking is working. No beeps from the immobiliser system either.

Quote:
Originally Posted by Man in the Car View Post
The fobs are powered by a CR2032 battery, and if the fob battery is weak it won't be able to transmit the signal for triggering the central locking.

The passive disarming of the immobiliser is done by the exciter ring around the ignition barrel which triggers the fob to transmit the signal to disarm the immobiliser. This will often still work even when the fob battery has become too weak to remotely operate the central locking. The passive disarming will not operate if the fob is not very close by the ignition barrel, and if it doesn't work you will normally just get a two-tone warning beep from the 5as unit behind the dash and the starter motor will not turn.

All your symptoms point to a short circuit somewhere, and the tailgate wiring loom is the probably the favourite, closely followed by the dash loom as mentioned by Talkingcars.

Good luck with finding the problem - these sort of issues can be a pain to find on occasions, but when you do find the problem, it is often fairly straightforward to fix
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post #12 of 27 (permalink) Old 04-12-2016, 17:03
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Quote:
Originally Posted by quantumDavey View Post
Looks like I have a very busy day today, Guys.

Thanks for all your suggestions and help so far.

I'm determined not to let this beat me ! I don't want to call an auto-electrician out, but if anyone knows of any good but reasonable guys (preferably "free and for the hell of it" guys, lol) around the Stockport area... (I know... I'm just dreaming, there !!)

Evry body, needs somebody... somebody to fixtheircar... someone to fixtheirelectrics.... fella to fix... and so on... lol


I had a similar electrical fault on mine, dashboard full of warning lights, alternator showing as not charging but was perfectly OK in the end. I used a mobile auto electrician not a million miles from you because I was at the end of my tether & this guy found the problem in under half an hour. it was a wiring fault that the previous owner had done that was shorting out under the dashboard.

I think it cost me 40 & well worth it. His number is G.S.A. auto electrics 01942 749051 07968199463
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post #13 of 27 (permalink) Old 04-12-2016, 18:40
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I'd check the tailgate loom next As MitC suggested...

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post #14 of 27 (permalink) Old 05-12-2016, 09:20 Thread Starter
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Talking

Sooo,

Okay, I think this has beaten me. I'm getting too cold trying to sort this thing out. Therefore I have called the guy you recommended. He's coming wednesday.

I don't like being beaten by things like this, but I've spent far too long p******ng in the wind with this now.

Quote:
Originally Posted by skeleboy View Post
I had a similar electrical fault on mine, dashboard full of warning lights, alternator showing as not charging but was perfectly OK in the end. I used a mobile auto electrician not a million miles from you because I was at the end of my tether & this guy found the problem in under half an hour. it was a wiring fault that the previous owner had done that was shorting out under the dashboard.

I think it cost me 40 & well worth it. His number is G.S.A. auto electrics 01942 749051 07968199463
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post #15 of 27 (permalink) Old 05-12-2016, 13:46
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Sooo,

Okay, I think this has beaten me. I'm getting too cold trying to sort this thing out. Therefore I have called the guy you recommended. He's coming wednesday.

I don't like being beaten by things like this, but I've spent far too long p******ng in the wind with this now.

I was in the same boat I'd spent a couple of days fault finding with no success, It was a fault I never would have found & it was worth getting a pro out to solve it & save my sanity.
He's a top bloke who knows his stuff. hope everything gets resolved.
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post #16 of 27 (permalink) Old 07-12-2016, 12:04 Thread Starter
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Smile Haha, yay, fixed.

The guy 'Geoff' arrived this morning, spent about half an hour on it and found the fault.

Problem with the contacts in the back of the ignition switch on position II. He put a temporary fix in to allow me to start the car (a toggle switch, to override the faulty contacts). I just need to get a replacement switch assembly for the back of the ignition switch if I can....

Anybody know the best place to get one ?

Car starts with only on kickover and engine runs smooth as silk ! Everything works, except the sunroof. I can live with that for now.

Hats off to Geoff ! And a big thanks to skeleboy for pointing him in my direction. He wasn't expensive either... 45 in my case as he had to come more than his normal range.

Verry, verry, verry

Last edited by quantumDavey; 07-12-2016 at 12:23.
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post #17 of 27 (permalink) Old 07-12-2016, 18:40
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The guy 'Geoff' arrived this morning, spent about half an hour on it and found the fault.

Problem with the contacts in the back of the ignition switch on position II. He put a temporary fix in to allow me to start the car (a toggle switch, to override the faulty contacts). I just need to get a replacement switch assembly for the back of the ignition switch if I can....

Anybody know the best place to get one ?

Car starts with only on kickover and engine runs smooth as silk ! Everything works, except the sunroof. I can live with that for now.

Hats off to Geoff ! And a big thanks to skeleboy for pointing him in my direction. He wasn't expensive either... 45 in my case as he had to come more than his normal range.

Verry, verry, verry

That's great news I'm glad he got to the bottom of the electrical fault, top bloke.
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post #18 of 27 (permalink) Old 13-12-2016, 12:13 Thread Starter
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Oh dear. Just put it in for MOT.... CAT gone, need new one, needs suspension arms and emissions through the roof. Engine wear.... needs overhall or replacement engine, just to get through MOT. If I could afford it, I would get it done... don't care about the negative equity regards the residual value. Unless I can get one fitted for under a few hundred pounds. Ha, fat chance. Problem is, engine 'sounds' perfectly fine.
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post #19 of 27 (permalink) Old 13-12-2016, 13:12
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.......emissions through the roof. Engine wear.... needs overhall or replacement engine......
I would be very surprised if the whole engine needs replacing.

More likely something else isn't working correctly. If the catalytic converter is duff, that will put the emissions 'through the roof' on its own - there are two on the non-VVC K series fitted to the 25 and ZR; one in the downpipe just below the exhaust manifold, and one under the floor-that is likely to be the one causing the emissions issue.
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post #20 of 27 (permalink) Old 13-12-2016, 13:19 Thread Starter
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They said when they took the filler cap off, the emissions went down, but not enough... There was also some rubbish fault coades on the ECU probably from the electrical fault which has been fixed.
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