Interesting. I have been avoiding disconnecting battery as lot of problems seem to be caused by it. Even reconnected gearbox ECU with battery connected as it was unplugged due to replacement not fixing the gear shifting and revving problem it was having. Also fitted TPS and crank sensor with battery connected.

It did start twice after the gearbox ECU plugging in. Once jumped second time normally after filling up. Hopefully have not fried BeCM. Think I will look at this main relay, did try swapping fuel pump relay with another one the other day but was not aware of the function of this main relay which can switch off ECU which would definitely cause the problems I have.

All wires to OBD11 looked good as did connector front and rear. I guess I have an engine ECU or BeCM problem but the problem could be simply that the engine ECU has no power due to this relay failing.

Am I trying to convince myself here or does this sound at all likely to anybody else?
 
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Sounds feasible.

For the record, I've never had any trouble disconnecting my battery.

Make sure the alarm is off before you do it. As a precaution I always leave a door open because I've read that reconnecting it can cause the locks to cycle, and if your key is inside you've locked yourself out!

Always disconnect the negative lead first.
 
Yes have been leaving window down as have locked out on a calibra turbo I had years ago. Had to smash window to get keys out. Have been disconnecting battery with key in ignition and think my 98 model has friendly re-sync where key picks up code when it goes in ignition.

Getting better towing quotes today as £340 is too steep. Think I need the car to hand so can try things and order parts as needed as it's an epic traveling back and forth to no avail.
 
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£100 to get towed home think I will do that as its 120 mile round trip and £10 day parking. Will have it home tonight
 
Do you think jumping it could have revealed a weakness in the fuse box and relay holder? Am increasingly feeling that maybe the ECU is not powering up resulting in no communication between it and BeCM.
 
ollyd said:
Do you think jumping it could have revealed a weakness in the fuse box and relay holder? Am increasingly feeling that maybe the ECU is not powering up resulting in no communication between it and BeCM.
Click to expand...
No, but voltage spikes cause by incorrect jump connections can do damage.
Fuse boxes are a common failure item. Easy enough to check for voltage at the ECU. Does the fuse box smell of burning?
 
Getting it back between 9 and 10 tonight so will check. Found my multi meter so can check ECU feed also. Breakdown man put + to + and - to - not to earth. It did start off key after this. It has been jumped several times since it has been immobilised though.

So I should check power to ECU and have a good look at fuse box for signs and smells of burning next.
 
Have kept re-sync tool so guess I will find out soon. Almost hoping there is no power to ECU as at least it will give a reason for the problems I have been having getting re-sync to work.
 
ollyd said:
Have kept re-sync tool so guess I will find out soon. Almost hoping there is no power to ECU as at least it will give a reason for the problems I have been having getting re-sync to work.
Click to expand...
Unplug the fuse box and check all connections. ( battery disconnected of course)
 
Will do, have seen its soldered together two boards back to back but will try and get a torch in and see if there are any obvious scorches. The wife is a dab hand with a soldering iron she used to make control units for traffic lights. Might have to get her involved if it looks dodgy.
 
Got it home now. Will check main engine relay and power to ECU then pull fuse box and inspect tomorrow. Also going to give battery a good charge as people seem to be of the opinion that BeCM needs a really well charged battery to operate properly.
 
At least now it's at home you can work on it in your own time.

Let us know how you're getting on!
 
Its on charge now about to start with fluke tests then onto fusebox and main relay. Will keep updated.
 
Battery is a Halfords HB075 56AH capacity when I look on their site 500 Amp starting power, I guess this is the CCA rating. Don't think this pen light battery will have been helping matters.

Does not have AHC on it so did not realise how puny it was until looked it up. Fuse box is out about to give it good inspection. Will probably get a 115 AHC + battery with at least 1000 CCA when I get her running.
 
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The biggest battery that will fit is an Alphaline 1000CC 130Ah battery from a place called Battery Megastore.

Loads of us have fitted them and are very happy, good price, quick delivery, and has sorted out many electrical niggles for lots of people on here.

It was about £100 delivered. I had to bend my battery strap to accommodate it when fitting (it is very big) but I've not had a problem with starting, or lock-outs since I did!
 
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