ECU Post Again!

[griffrhysjones]

As most of you will be aware I am realitive new comer to the world of TVR and most of you will also be aware that I keep having major ECU problems, ie. they only last 200 miles! After 3 replacement ECU's may faith has become well and truly tested. Does anyone know the most common fault which cause ECU's to burn out? I am not even having much luck in getting it to a specialist as they seem a bit thin on the ground in this neck of the woods, any help appreciated otherwise it may be destined for the classifieds! Simon.

[GarryM]

In my case, a lambda sensor and the ECU went at the same time. Could have been the lambda that did for the ECU or the other way round I suppose but I mention it just in case. Hope you get it sorted - that sounds like a very expensive business.

[mel]

It might help but when I entered the ECU part number off of mine on a google search it turned up and exchange a diagnostics centre that did a dirt cheap exchange unit. Sorry I can't remember what they were called but they were in the midlands somewhere, try the google path.

[mongoose]

i imagine youve checked the integrity of the wiring everywhere as much as poss?no damaged shorting out ecu sensors?then i think i'd be inclined to try a new alternator as you could possibly be getting intermittent voltage spikes,a/c supply or somesuch.

[spend]

griffrhysjones said:

Does anyone know the most common fault which cause ECU's to burn out?

I would hazard a guess that touching the ecu casing on the battery positive terminal is the #1 cause of this type of failure. Not saying it is in your case, just answering the question..

Dave

[starmist]

A common fault in Griffs, when you site the ECU on top of the battery is shorting out from the fuse board. If you look at the board, there are two unprotected copper bus bars - both very live.

Coupled with a metal, earthed casing for the ECU, and if one touched the other, smoked ECU!

Get some duck tape and cover the two bus bars, or find somewhere else to site the ECU.

Mark Adams can repair most fried ECUs. It'll cost you £7.00 odd to datapost it to him, if you're nowhere near Shropshire.

[spend]

I assume the bars you refer to are the studs to fix a strip fuse to. Most Fuse boxes have these covered with sealant, both of them should never be live. If fuse 13 is in use the centralmost one may be live, but the other stud is only connected to a large spade (terminal N) at the back of the fusebox (main live input if the fused link is to be used). As well as fuse 13, the centralmost stud is connected to a large spade at the back (terminal O) and into the adjacent relay - never used on TVR but I believe is for the glow plugs on VW or something like?

HTH, Dave

[griffter]

griffrhysjones said:

As most of you will be aware I am realitive new comer to the world of TVR and most of you will also be aware that I keep having major ECU problems, ie. they only last 200 miles! After 3 replacement ECU's may faith has become well and truly tested. Does anyone know the most common fault which cause ECU's to burn out? I am not even having much luck in getting it to a specialist as they seem a bit thin on the ground in this neck of the woods, any help appreciated otherwise it may be destined for the classifieds! Simon.

Having overhauled as much of the wiring as I can get to - by stripping most of the interior, and enduring amazing feats of contortion in the the engine bay and underneath the car, I can only suggest the problem lies in the loom somewhere. There are a number of places where diodes are fitted in series with wires. I never figured out what the wires are for - but the diodes are there for a reason, maybe to stop back voltage spikes? Anyway there's one taped up in the loom running to the ecu where the loom drops into the passenger footwell - you'll have to remove all the loom tape to find it. There's another (possibly two) in the loose wires running into the fusebox. You'll need to carefully remove the fusebox to inspect. As I say I don't know what the diodes are for - but they are probably to protect some delicate circuitry - eg ecu. If they've ever failed and been simply removed as a 'quick fix' you might get the sort of issue you're up against now. Are the relays in the loom the silver metal Bosch type? These have diodes integral with them.

Secondly, in a number of places, slightly (!) slap-dash construction led to wires being trapped (eg between fusebox shell and firewall) or even drilled into (the loom above the glove box where it runs under the base of the windscreen). I can only imagine the nightmare these would cause if a damaged wire broke completely or shorted. How on earth would you work out where the problem was?! You can only find these things by tearing the car apart and looking at every bit of it. So...check as much of the loom as you can and when you reach your limit of patience/ability, drop it in at a respected specialist and leave it with them for as long as it takes.

Finally I discovered some truly horrendous wiring bodges during previous ownership, to bypass aspects of the fusebox - due only to corroded fuses. Cleaned up the fusebox, replaced the fuses, and all seems OK. Yours being a precat may have suffered such 'repair' in the past. Have a go yourself but if in doubt hand it to a capable specialist.

[red griff 500]

If the fault isn't relatively obvious i.e. the ECU case shorting onto a live somewhere, then another possibility is to try to diagnose the fault by finding out which part of the ECU circuit is failing, this could narrow the search for the cause. It may be obvious when you open up the ECU box e.g. a blown component. You'll need a circuit diagram which may be available from Lucas(?).

Good luck

Steve

[griffrhysjones]

Thanks for the suggestions, as the ECU company have refused to repair it under warranty I felt I had nothing to lose by opening it up, found a horrific bodged repair with a piece of wire and some silicone so many thanks to tunemycar.com for their last warranty repair, it has become clear that is the 3rd pin in on the middle row, (counting from the moveable clip end) does anyone now where I can get the pinout diagram? Simon.

[starmist]

You could do alot worse than speak to Mark Adams. At least one of the Busbars IS live, as I've shorted mine out before.

Anyone know what the fusebox is from?

As anyone tried relocating it so somewhere more accessible, such as the boot? I would be very interested in doing this / paying for someone else to do it coupled with fitting a small solid battery, such as those that can be found in Demon Tweaks.

[david beer]

Differcult to see from the Rangie manual which is the end you are talking.3rd in one end,is it blue/purple, fuel pump trigger. Red/black supply for airflow/throttle pot/fuel temp/coolant sensor. If so, sounds more likely than the fuel relay. Of course yours may be completely different !!

[topsparks]

I fried my ecu jump starting the Griff a couple of weeks ago,a friend of mine recomended the ecu doctor,he repaired my ecu for £170 with a years warranty.His number is 01752 346437 and he is a nice bloke,regards James.

[griffter]

starmist said:

Anyone know what the fusebox is from?

Mine ('92) is VAG - Golf I think. Don't know about the 500.

starmist said:

As anyone tried relocating it so somewhere more accessible, such as the boot? I would be very interested in doing this / paying for someone else to do it coupled with fitting a small solid battery, such as those that can be found in Demon Tweaks.

It's not too bad to get it out (bit harder to get back) and quite accessible once removed. Relocating it to somewhere as radical as the boot would require an extension to the entire loom.

[starmist]

I realise I'd have to extend the loom, just wondered if anyone had done it.

[steve-v8s]

On the battery point, I have been running a Red Top 20 for about a year now. (D-Tweeks were a bit expensive though) gives more leg room, more ECU room and a lot less weight too. Tend not to use the car in the winter so don't know how it would cope with that.

[starmist]

steve-v8s said:

On the battery point, I have been running a Red Top 20 for about a year now. (D-Tweeks were a bit expensive though) gives more leg room, more ECU room and a lot less weight too. Tend not to use the car in the winter so don't know how it would cope with that.

Very interesting, as I was looking at the red top 25, as it has a greater cranking current. Where did you get yours from, as I think Tweaks want about £82.00 for the 25?