Strange Electrical Going On

[robwright]

Ok it's been a funny old day as Arkwright would say. On the way to work this morning on the A1 the car completely died - LOST EVERYTHING!!!. Thankfully I was able coast into a layby just outside RAF Wittering - handy place to leave your car. After several attempts to get started again this is what was happening. The dash would light up and go out on and off and on and off etc accompanied by relay chatter. Checking under the bonnet proved that the DME relay was indeed chattering. I thought great I wish I had listened to all those posts that said that a DME relay is a good spare to carry in your glove box [][][]

Pretty soon after the cavalry arrives in the form of her in doors to get me to work. Anyway the only place I can get a DME relay from by the end of the day was OPC Cambridge at a price of nearly £60!!!! Not so well done OPC on that one. Having no other choice but to buy it her in doors turns up and we travel the 80 mile round trip to Cambridge to pick it up. Get to my poor lonely turbo in the layby and fit said relay. Ignition on and the dash bursts into life - GREAT!!!!! Turn the key and crank, crank, crank but no start [&:] As a long shot I put the old relay back in and she fired on the first turn of the key.

So firstly it looks like the overpriced relay that OPC sold me is a duffer and is not running the fuel pump but hey I can live with that these things happen. The thing is now that the car is running fine but here is the strange thing. My immobiliser which usually flashes and I stick the torpedo in to disarm it no longer does it is extinguished. When I turn the ignition key though it lights solid (which is normal for disabled) and the car starts without me sticking the torperdo in [&:][&:][&:]

So the thing is is my old DME relay dodgy and has effected my immobiliser or has the immobiliser been screwing around with my electrics???? The thing that gets me is when the immobiliser was functioning properly it would never stop the dash from bursting into life only stop you from cranking the car. Is it time for the immo biliser to be ripped out? Thoughts anyone please.

 

[944 man]

The first line suggests an earth fault to me (main earth strap), but the rest leaves me confused.


Simon

 

[robwright]

Yes confused also mate hence the post. I am normally a whizz with the electrickery stuff. It's one of the many fields I work in but this one got me stumped brother [&:] I will figure it out eventually I normally do but it's a bit difficult when she is your daily driver. It can rock your confidence a bit especially when she has never let me down before.

 

[Lowtimer]

I regret I can't help from a position of strength, but I must admit I always scowl suspiciously at immobilisers and don't really like having one on my car, though I supose it's sadly a necessity. However, it seems like asking for trouble to fit a machine with a complicated device designed exclusively to prevent the thing working. When your engine quit, was the dash flashing on and off then, or did it stay on?

I would be tempted to try the DME relay that came from OPC Cambridge on another car if possible to see if it checks out. At ;least it would be another data point. I might also try putting that relay back into your own car and giving it another try, to see if it is reliably and consistently not working.

 

[robwright]

Already stuck the relay that I got from OPC back in the car as soon as I got home. Result was exactly the same crank but no start. The relay is definitely a duffer!!! I am seriously tempted to rip the immobiliser out tomorrow. Was thinking of fitting a new thatcham cat 1 alarm + immobiliser anyway.

 

[alwigley]

Might be worth bypassing the DME relay completely to eliminate the fault - 3 way cable with male spade connectors into the 3 largest slots on the relay space on the fuse board (top, middle left & middle right I think) should do the trick from memory (I carry this in the glove box !), just don't forget to disconnect when parked as it permanently live wires the fuel pump........... Clarks Garage gives proper details []

 

[peanut]

yes a 3x way bypass is the way to go Wiggley.

You fit terminal 87 and 87b first then terminal 30 last as terminal 30 is the constant 12v+ live feed from the battery.

This will over-ride the ECU and sensors and give you continuous fuel pumping and ignition.

By the sound of it , it is not your relay that is at fault but the earth to your DME relay feed or the 12v+ supply to terminal 30 on the DME socket.
Try wiggling the ignition key and its wiring connector next time it happens it could be a worn /faulty ignition switch as there is a second supply to the DME relay from terminal 15 I believe from memory

The three crucial earthing points that you should check and clean also are GP1, GPll , and GPlll
GPl is the earth for the fuel pump
GPll & GPlll are earths for the DME and ECU

 

[robwright]

OK situation update. Had a few hours spare at work this afternoon so decided to look into the immobiliser issue. Well when I say look into I mean rip out. No sooner had I got the unit out of the car then about half a gallon of what can only be described as Ganges water poured out the bottom of it. Where it came from I just don't know. It was located behind the DME and everything in there was perfectly dry. Still at least I got to the bottom of the mystery and it was the immobiliser after all that. To be honest I am not sad that it came out as it was by far the worst wiring job I had ever seen in my life and I have seen some sights. Thing is I have the original installation certificate from the garage that fitted it. It makes you laugh that the insurance insist that you supply this when as far as I am concerned it was not worth the paper it was written on due to the clown that installed it. God only knows how it managed to stay working for so long. I suppose at least now I have an excuse to get a proper cat 1 alarm and immobiliser and fit the bloody thing properly. The upshot of it all was I finally got round to making up a set of DME jumper leads to bypass the DME in the event of failure. Far cheaper than buying a spare relay []

 

[Northern924]

Good to hear you got the bottom of quickly, nothing worse than an ongoing electrical problem you can't pin down.

Talking about the relay, anyone looking to get a spare, remember to look for one from an Astra or Nova GTE as well.........SAME RELAY []

 

[DivineE]

Good advice thread this. Anyone know the part number/cost for the Astra part? I think I will kill myself if I get a wiring fault with WUF as I have absolutely no idea how the three new ECU's are connected, how they work or what they are wired to. All I know is, removing the DME relay still kills the car.

 

[Diver944]

ORIGINAL: DivineE

I think I will kill myself if I get a wiring fault with WUF as I have absolutely no idea how the three new ECU's are connected, how they work or what they are wired to.

Did you sign up to Ricks 3 year maintenance/servicing deal when you bought it?

 

[Northern924]

Not sure what the part no. is for the Vauxhall one, will have to pop the bonnet tomorrow to find out (well I'm not going to wear out the Porsche one first now am I [] )

Have a look on ebay, £4.99 a go (or have a gtrip to your local scrapyard they were used in the Cavalier as well)

 

[robwright]

Ok treated myself to a new thatcham cat 1 alarm & immobiliser. A little daunting at first to fit although like everything else once you get into it's not too bad. Very pleased with the results anyway. No more messing around with sticking things into orifices to immobilise the car just a single remote key press and done. Also that means I now have remote central locking which is a pretty nice bonus [] Just contemplating wheteher I CBA to wire the windows to close from the remote but not sure if I will bother. I know there may be others out there thinking about fitting one so if you ever need a hand then PM me or call me. For obvious reasons I don't want to publish the details of fitting it in the technical articles section.

 

[DivineE]

haha good work. Whick brand did you go for? There always seems to be strong arguments for both the Toad and Clifford camps. I've always liked Clifford providing you a. don't let the battery die and b. use valet mode when washing the car so it doesn't go off every 20secs[]

 

[robwright]

I went for the Toad Sterling One alarm mate. Incidentally they are now owned by Scorpion. I think they are all pretty much the same in function. Glad I upgraded now though.