ECU woes

[Anton Sobriquet 0]

I have an intermittent non-start on my '94 VR6 (could be bad earths, and I'll clean those up asap), which led me to inspect the ECU with a view to insulating it inside a plastic bag. After unscrewing the nut from the bracket and pulling the unit out, I found to my horror that the large bunch of wires aren't really properly connected into the side of the ECU connector. It looks as though the wrong connector/seal has been used. Also a black/green wire has been stripped at some time and just has a tatty piece of insulating tape around it. Looks like I'll be spending some time with a soldering iron and some shrink wrap!

 

Main problem I've got is I can't disconnect the connector/seal from the ECU unit so I can remove the latter and start to try to get to grips with the cables going into the connector. How do I do it? There's nothing much to get hold of with fingers. I looked carefully and poked about with a screwdriver but succeeded only in pulling the black plastic off the connector slightly on one side and can't work it out. Probably being dim. I've got the Corrado USA manual but it doesn't help at all (only has AAA engine with distributor).

 

Can anyone help, please? And does anyone have a wiring diagram for the connector into the ECU?

[KipVR 1]

I might be able to help you in a while with a new loom/connector/ECU/keys if you need one. Mine will all be redundant soon, I'm afraid I can't answer your question though... :lol:

[Anton Sobriquet 0]

Yep. I'll take you up on that, thanks.

[CrazyDave 0]

Looking at the ECU from the front of the car when it's in place under the scuttle.

 

The connector is on the right with the loom coming towards you, at the same end as the wiring loom comes out and to the left should be a clip that you pull towards the front of the car. As you pull the clip towards the front of the car the plug will slide out to the right.

 

Should come out really easy (ie without have to use tools, just fingers). What you might have is an early ecu on a late car, the ecu connector on later cars have polarising pins to stop fitting an early ecu to a late car. But they are the same connector so if you remove the pips they'll fit but usually the connector will be really tight.

 

Sounds like the offer of another loom that's not been hacked about is worth going for though....

[mattkh 0]

I have an intermittent non-start on my '94 VR6 (could be bad earths, and I'll clean those up asap), which led me to inspect the ECU

Main problem I've got is I can't disconnect the connector/seal from the ECU unit so I can remove the latter and start to try to get to grips with the cables going into the connector.

hi

Please take some photos and put a link up.

[Anton Sobriquet 0]

Just back from the garage and was about to post the 'how to' of getting the connector off, but CrazyDave beat me to it. Thanks for that, as you say, dead simple when you can see what you're doing. Pulling the black plastic fastening clip towards you releases the connector.

 

I took the ECU off, cleaned it and dried and tidied up the whole scuttle area, which was full of dead leaves and had been getting wet via a badly fitting scuttle cover (turned out to have been broken and glued back on) with the muck then presumably staying thoroughly damp all around the ECU. I dismantled the connector into its various parts and cleaned up all the contacts and reinsulated the green/black wire which had been stripped. I found a thick pale blue/red wire also had insulating tape around it, but in much better condition than the green/black, so I left it as is. I managed to stretch the rubber boot to cover most of the loom going into the connector (from the engine bay through the scuttle), but I'm pretty sure there's a gap right at the back on the tight curve/twist of the loom, and that the wires are exposed there.

 

The problem with the connector seems to be that the rubber boot over the loom from the scuttle terminates in a circular style moulding, which doesn't look as though it was designed to fit the connector. It's possible it's broken and a piece is missing, but I don't have an illustration of how it should look. It does look very much as though there are parts from different cars cobbled together. If anyone has a pic or illustration of the VR6 ECU/connector assembly as it should be that they could post, it would be very much appreciated. I'll take some pics of mine tomorrow to post up and show you how it looks.

 

Anyway I refitted everything, since it was getting dark and cold (and I needed a coffee and a fag) finishing with a new SWG scuttle cover (for which I'm going to need a couple of large rubber washers to seal around the wipers), which does seem to seal between scuttle and the base of the windscreen. Hopefully, the end of water and leaf ingress. And yes - she fired up straightaway no problem! Pending the arrival of an unmolested loom etc from KipVR in due course, or finding the correct or whole boot/connector, I'll open it up again tomorrow and put the whole ECU/connector assembly inside a few plastic bags to help keep everything clean & dry.

 

I read somewhere recently that only the very late models' ECU has an immobiliser built in? Is this the case? I had an aftermarket alarm fitted (non-professionally by the look of it) when I bought the car, which I had removed when I thought it might be causing my occasional non-start if its immobiliser wasn't clearing. I'm starting to wonder if there's a connection (sorry pun unintended), and the non-start is actually being caused by an ECU immobiliser I didn't know about, so that she will crank but won't fire on the occasions she won't start (should check for spark when it happens, eh?). I'm also now wondering whether I need to renew my ignition switch, which I have heard causes problems with the immobiliser when it is faulty. Can anyone help explain, please? I'm very confused about immobiliser/alarms and how they work.

[mattkh 0]

I found a thick pale blue/red wire also had insulating tape around it, .

Hi

Take the insulating tape off to see if the wires are just twisted round. If they are then solder them and insulate.

Check the connections where the alarm/immobiliser was spliced in to the ignition wires near the fusebox. Again if they are just twisted together, solder them and insulate.

As regards the plastic bag around the ECU, I think that will cause more moisture to stay in.

Look forward to the photos.

[dr_mat 0]

I read somewhere recently that only the very late models' ECU has an immobiliser built in? Is this the case?

 

Yes, the xxx CP named ECUs have an immobiliser built in. There's a reader coil around the steering column that picks up the ID from the chip in your key. BUT typically if this setup isn't working the car will start, then cut out immediately, it doesn't generally prevent initial startup.

[Kevin Bacon 5]

I suspect your car has had a schrick manifold on it at some point.

 

Red/blue is the main ignition live feed to the ECU

Green/black is the rpm signal wire

 

These would have been tapped into to supply the Schrick controller box.

 

I could be wrong but I can't think of any other reason why you would hack into those two wires.

 

Don't worry about the ECU connector, they are waterproof, despite how it looks. Each pin has a water proof seal underneath the cable cover, the ECU plug has a water seal and the ECU cover has a water seal. You can drop the whole lot in a bucket of water and it would still work.

 

I don't think you have a problem, other than someone not tidying up after themselves when taking the schrick off.

[Anton Sobriquet 0]

Interesting.......... Assumed something had been connected into the loom there but wasn't sure what it might have been. Makes sense.

 

I managed to get a look on ETKA at the rubber boot between scuttle (plenum chamber?) and connector and there's defo a bit missing from mine. I was worried that moisture might penetrate, not so much into the connector/ECU but into the wires in the loom where they are exposed, especially where they've been spliced. I can probably remedy that with some hose and tape until I can replace it. I take the point about trapping moisture if the whole connector/ECU assembly is wrapped in plastic bags.

 

Reassured that you think the ECU's OK, although I had managed to justify an OBDII conversion to myself on the strength of it having been messed about with :D .

[Anton Sobriquet 0]

Should have posted this ages ago, just to wind it up.

 

It turned out the ECU was perfectly OK and the intermittent non-start was a faulty ignition switch. A mate and I spent about 3 hours messing about trying to replace it, following the guide in the wiki. It's unbelievably fiddly, particularly as the screw holding the switch in is brass and we ended up having to carve a new slot in it after smoothing the head. But we got there in the end and the car fires up like a good 'un now. Wouldn't want to have to do it agin, tho'...

 

I went for an OBD2 conversion in the end, as per sig, and must say it's a huge improvement. Well worth it. Engine is much more lively and responsive. Only snag is I've got a faulty reading on the MFA output for MPG - it permanently reads 99.9 :lol: Otherwise everything works.