Hi all,

the workhorse GP has had a niggling fault since I bought the car, which I think I'm narrowing down now, however my knowledge of the electrical system in these cars is limited, so I'm hoping someone here can point me in a direction to look in.

Firstly a brief explanation of where I am at. I bought the car last November, it had a busted light bulb warning light on the dash. I went through and replaced both rear number plate lights, OS rear side light, NS front sidelight, and the dash warning was gone. Result I thought.......it went through and passed MOT.

Started using the car as a daily and noticed that sometimes the light warning on the dash would come on then go off, so I started to pay attention to try and see if there was a sequence and it appeared to show it self mostly when either lights are on and I indicate left or right at the same time, or brakes are on and I indicate left or right. As usual checked all bulbs again and all is good there.

A friend recently said to me, check your lights with everything turned on, hazards, lights, fogs, etc. it likely to be an earth problem. I did and confirmed the rear lights were doing the disco (this is to say when the indicator is on the other lights will dim in response to the indicator coming on, then return during off........you get the idea).

So yesterday I took both rear light clusters off, looked at the contacts, brushed what I could with a small wire brush then refitted.

I then went into the engine bay and completely removed the negative terminal from the battery, followed the wire down, disconnected from the chassis leg inner, then from the gearbox front. Took the wire aside and brushed all terminals to a shine, then the chassis/gearbox mounting points too. Refitted and greased over the bolts/nuts where appropriate.

I also noticed a ground point just above the ECU (located on top of the opposite side chassis leg/OS) that was coming from a T-piece of the wiring loom. Took that off and scrubbed the terminal and the chassis point then refitted and greased over.

Done a test with all lights blazing and.........
1. The OS rear is now good.
2. The NS rear is the same if not a tiny bit worse.

In summary I did 3 ground points in the engine compartment and cleaned the light cluster contacts and connectors.

Are there any other wiring grounding points in the GP that I should be looking for? I couldn't find anymore inside the cabin under carpets or in the engine bay area.

The car is a 2007 1.3Mjet 75HP 5 door Manual.

I would appreciate any pointers on the wiring of the GP which may lead me to an area I have missed out. I already looked at the guide on the 1.2 engines but the ground points in the engine compartment are in different places to the mjet.

Humour

P.S. other than that annoyance, after I changed the clutch and cleaned up the flywheel from years of clutch dust collecting in there, the car has been a peach and a joy to drive (slowly) lol.... it is a tad pedestrian but I'm almost used to it now.

I know it might seem like a simple solution, but have you tried changing the battery? The 1.3 eats through batteries, and if you've had the original last 7 years then you've done very well. Very common for it to throw stupid errors (e.g. 'high coolant temperature' when starting from cold ) when the battery's on its last legs.

Fair point Cadabena. Your advise may prove to be the eventual course of action.

However, I have no reason to suspect the battery just yet, it has never struggled to turn the engine over during the winter or at this time of year, add to that that I have no other funky errors coming up, so I'm concentrating on some of the basics without having to shell out cash in an attempt to fix the problem. I've done that on another car for 8 years now and the result is almost always the same.......unfortunately.

Given that I played with the light clusters and some of the engine grounding points already which cured the OS rear cluster, my educated guess is that it is wiring/contact related......however I am more than likely going to be proven wrong when I change the battery as the last measure lol.

When I got the car, the NS inner arch liner/dust cover was missing and the various connectors in that area in and around the fuse box were a right mess and covered in mud I replaced the liner soon after I discovered the issue, but I didn't touch the connectors too much other than to wash the area with water spray to get the dirt off. Now thinking back, it might have been a good idea to give everything in that area a closer inspection by unplugging the connectors and checking the condition of the pins etc. but at the time I didn't have the time to mess around with it too much.

The question is, is there a grounding point in the area around the fuse box that I was unable to see, bearing in mind there is one on the opposite side, hence my initial query in this thread. It's a long shot I suppose given that if there is one, it's hidden enough that its not easily found, so its unlikely someone will know unless they have had to go through chasing a possible earth fault like me.

Humour

Check for water in fuse box...

If it's flashing rear light clusters that's where the problem is.

I know you have already taken it apart, but everything needs cleaning. Water gets into the rear light clusters through damaged washer hoses that leak.

The whole light cluster needs to be taken apart. All the silver tracks need cleaning, the bulb holder needs cleaning and the base of the bulbs themselves or just replace them. The white connector that plugs into the light unit needs cleaning as do the connectors that it clips into.

Do this using electrical cleaner and a stiff brush like the small toothbrush wire brushes you can get.

They start to corpse and short circuit causing the stupid disco effect.

Thanks Jimbob,

I was thinking that is likely to be the area to concentrate on, however since I also messed with the ground points in the engine bay at the same time, I wasn't sure what task fixed the OS rear cluster.

If it's a case of the light clusters showing their age (although the tracks all looked clean when I took them apart), then perhaps it's a good enough excuse to go Abarth rear clusters? :idea: Then I only have to worry about cleaning the white connector pins.

Humour