OOOOPS...........

[billybradshaw]

Erm........where should I begin?

Whilst removing the old front dampers off my car one of the lower bolts become stuck. Rather than fanny about I whipped out the grinder and hacked the bugger off. In doing so I grazed one of the spacers. Not to worry thought I, a bit of weld followed by a tickle with a power-file and a 1/2" reamer all will be well. So I dusted off my trusty MIG, got everything ready and disconnected the car battery...............OH SH*T!!! I didn't disconnect the battery when I welded a nut onto that rounded off b*stard of a diff plug the other day.......

I quickly hooked the battery back up, jumped in the drivers seat and pressed the ignition button. I was greeted by an illuminated dash, etc, etc. The engine turns over, the fuel pump pumps. I can't actually start the car because of the neighbours and it being quite late in the day. However, my worry is that I don't have a MIL light shining and also when it came to turning off the ignition, I couldn't. The red button did absolutely nowt.

So, I guess I'm looking for some man hugs and assurances that I haven't screwed up anything major and some explanation perhaps as to why no MIL light and a dysfunctional red button.

Yours

Stupid of

Standish

[ianwhitewick]

Have a beer!

I hope it's just a fuse (or equally cheap)!

[GT6k]

I don't see what difference having the battery connected makes to it. A more logical protection would be to disconnect the ECU. The main thing is to make sure the welder earth is properly connected to component you are actually welding. Years ago I quickly re-welded a captive nut on a wishbone and then had the braided brake line red hot as it was the only earth path to the suspension.

[billybradshaw]

GT6k said:

I don't see what difference having the battery connected makes to it. A more logical protection would be to disconnect the ECU. The main thing is to make sure the welder earth is properly connected to component you are actually welding. Years ago I quickly re-welded a captive nut on a wishbone and then had the braided brake line red hot as it was the only earth path to the suspension.

Thanks for that. I had the earth from the MIG attached to the case of the diff no more than 4" away from the drain plug.

I really don't do electrics / electronics as I'm colour blind and I've compartmentalised the whole discipline into the 'all too difficult box'. Don't know where to start with this one.

Ian

[tofts]

I must be honest, I am "slightly" concerned as to the reason the red button would no longer work. But the fact that the black button is fine, shows that the IGN ecu could be ok.

HOWEVER, those in the know, know that current will take ALL paths to ground regardless. So even a ground close to your work piece can cause current to flow through extraneous conductive parts. With this, disconnecting the battery is of up most importance, and considering the cerbera has 9 additional control units apart from the engine ECU, it is theoretically wise to disconnect them all. From experience though, it is generally fine so long as you disconnect the battery alone.

Given the red button is just a "pull low" input to the IGN ecu, you can test to see if the button, or the IGN ecu is at fault. If today, its still not working, I can give you a couple of quick checks to test.

[billybradshaw]

tofts said:

I must be honest, I am "slightly" concerned as to the reason the red button would no longer work. But the fact that the black button is fine, shows that the IGN ecu could be ok.

HOWEVER, those in the know, know that current will take ALL paths to ground regardless. So even a ground close to your work piece can cause current to flow through extraneous conductive parts. With this, disconnecting the battery is of up most importance, and considering the cerbera has 9 additional control units apart from the engine ECU, it is theoretically wise to disconnect them all. From experience though, it is generally fine so long as you disconnect the battery alone.

Given the red button is just a "pull low" input to the IGN ecu, you can test to see if the button, or the IGN ecu is at fault. If today, its still not working, I can give you a couple of quick checks to test.

Thanks tofts. The only other things I have done at around the same time as the welding job are the removal of the LH interior door panel and I've removed the radio. I'm hoping that maybe I have disturbed a connection / ribbon cable. I'll do some basic physical connection checks but if you can point me in the direction of some functional checks too that would be great.

Thanks again

Ian

[tofts]

The first and obvious ( as you said) is check connections, there is a black square ish multiplug under the steering column that connects the pod to the loom, just cycling the plug can sometimes be enough to find the fault. If not, there is another connector under the rear helmet pod but its unlikely this is the issue, so go straight in to the boot and on the left of the top of the fuel tank is your IGN ecu. Again, cycle the plug a couple of times and check pins for corrosion etc.

If still no joy then with the ign ON and assuming the red button does not work. In the front of the car under the pod get a piece of wire or suitable multimeter lead with a small pointed end and find a suitable ground to connect to (The steering column bolts should be nice and shiney). Touching ground to the BLACK/RED wire of the multi-plug should turn the car off. If it does not, then repeat the process but at the ign ECU directly, same BLACK/RED wire. If it still does not, then its a duff IGN ECU. If it turns off, then there is a switch issue, or wire issue from front to back.

DO NOT, probe any solid RED or solid GREEN wires, these are LIVE and SWITCHED LIVE respectively.

If your uncomfortable with the process, I can probably get some pics of the plugs and wires a bit later if you wish, but its actually quite easy and nothing to worry about.

If its a switch, then you can order them from rapid (http://www.rapidonline.com/electronic-components/itw-ip67-sealed-momentary-push-button-switches-81473).
if its a control unit, then I can probably repair it for you. Won't bore you with the crap, but so long as you haven't fried the micro controller they can be repaired quite easily. If you have fried the micro controller, It can be repaired all the same, but needs a new micro controller and reprogramming, which again I can do.

Jody

Edited by tofts on Thursday 3rd March 10:22

[billybradshaw]

tofts said:

The first and obvious ( as you said) is check connections, there is a black square ish multiplug under the steering column that connects the pod to the loom, just cycling the plug can sometimes be enough to find the fault. If not, there is another connector under the rear helmet pod but its unlikely this is the issue, so go straight in to the boot and on the left of the top of the fuel tank is your IGN ecu. Again, cycle the plug a couple of times and check pins for corrosion etc.

If still no joy then with the ign ON and assuming the red button does not work. In the front of the car under the pod get a piece of wire or suitable multimeter lead with a small pointed end and find a suitable ground to connect to (The steering column bolts should be nice and shiney). Touching ground to the BLACK/RED wire of the multi-plug should turn the car off. If it does not, then repeat the process but at the ign ECU directly, same BLACK/RED wire. If it still does not, then its a duff IGN ECU. If it turns off, then there is a switch issue, or wire issue from front to back.

DO NOT, probe any solid RED or solid GREEN wires, these are LIVE and SWITCHED LIVE respectively.

If your uncomfortable with the process, I can probably get some pics of the plugs and wires a bit later if you wish, but its actually quite easy and nothing to worry about.

Jody

I'll have a crack at this tonight and report back with my findings.

Would a duff Ignition ECU relate to the MIL light not illuminating?

Thanks for your help Jody

Ian

[tofts]

Ahh yes, the MIL light is controlled directly by the ECU through the dashboard, you said the fuel pump primed? If so, then the ECU is fine, as its controlled from this, and shows the ECU is initialising correctly. Does your handbrake warning light come up when the ignition is on, if not then try FU7 (i think). All dashboard lights are controlled via this.

[billybradshaw]

tofts said:

Ahh yes, the MIL light is controlled directly by the ECU through the dashboard, you said the fuel pump primed? If so, then the ECU is fine, as its controlled from this, and shows the ECU is initialising correctly. Does your handbrake warning light come up when the ignition is on, if not then try FU7 (i think). All dashboard lights are controlled via this.

WOO HOO, yes the fuel pump primes so the main ECU is fine, thank goodness for that.

I forgot to mention that the handbrake warning light didn't illuminate either. I'll check the fuse.

I can't thank enough for your help so far Jody.

Ta

Ian

[billybradshaw]

Quick update:

Fuse 7 is in rude health, all dash lights work except handbrake and MIL

I've taken the BLACK/RED wire to ground at either end and the ignition only turns off at the module end so it looks like a switch issue after all, PHEW. Following the link Jody I can see two variants of the switch, which part number should I order?

I've also done some quick spannering and fired up the wee beasty. Considering it hasn't run in 6 months it was as sweet as nut. Presumably this entirely rules out the main ECU having a problem and I have permission to look a little happier than I did last night )))

So with your help Jody I'm getting there thank you.

I just need to get my head round the MIL light now.

Cheers

Ian

[tofts]

well, actually, if it works at ecu end but not the dash end then it suggests a wiring issue. The wire at the front you pulled to ground is after the switch and so should have worked!

If you have a multimeter, try seeing if there is continuity between the black/red to ground from the front of the car with the button pressed. What your saying suggests the reading will be ok, in which case it could be the entirely unlikely connectors under the rear pod or a chaffed wire...

Permission is granted to look happy, but remember to disconnect that battery next time!

edit: rapid out of stock. try http://uk.rs-online.com/web/p/push-button-switches... but not until you know its the switch!!

Edited by tofts on Thursday 3rd March 19:28

[billybradshaw]

tofts said:

well, actually, if it works at ecu end but not the dash end then it suggests a wiring issue. The wire at the front you pulled to ground is after the switch and so should have worked!

If you have a multimeter, try seeing if there is continuity between the black/red to ground from the front of the car with the button pressed. What your saying suggests the reading will be ok, in which case it could be the entirely unlikely connectors under the rear pod or a chaffed wire...

Permission is granted to look happy, but remember to disconnect that battery next time!

edit: rapid out of stock. try http://uk.rs-online.com/web/p/push-button-switches... but not until you know its the switch!!

Edited by tofts on Thursday 3rd March 19:28

Right then, the little ones are tucked up in bed so I'll go and check for continuity.

Any thoughts on the blummin' MIL and handbrake lights? I'll stick my DVM directly to them and see if they illuminate to at least rule out knackered LEDs.

Cheers

Ian

[tofts]

The handbrake light and the brake fluid light share the same common circuitry. take the cap off the resevoir, so it bottoms out and activates the float switch, or take the plug off and bridge the 2 wires together (latter if brake fluid is your nemesis) see if the light comes in then. If so then theres an earth issue with the handbrake/wiring. If not then its the circuitry/dashboard.

Does the buzzer come on as normal through the ignition process? If not then its definitely a dash power issue. I only made a good guess at no7 I may actually be wrong, as its a little ambiguous.

Hang on, what year is your car? there was a fusebox change on later models, and fuse 7 is headlights off the top of my head? Either way, does radio turn on, as its the same fuse?

Edited by tofts on Thursday 3rd March 21:31

[billybradshaw]

tofts said:

The handbrake light and the brake fluid light share the same common circuitry. take the cap off the resevoir, so it bottoms out and activates the float switch, or take the plug off and bridge the 2 wires together (latter if brake fluid is your nemesis) see if the light comes in then. If so then theres an earth issue with the handbrake/wiring. If not then its the circuitry/dashboard.

Does the buzzer come on as normal through the ignition process? If not then its definitely a dash power issue. I only made a good guess at no7 I may actually be wrong, as its a little ambiguous.

Hang on, what year is your car? there was a fusebox change on later models, and fuse 7 is headlights off the top of my head? Either way, does radio turn on, as its the same fuse?

Edited by tofts on Thursday 3rd March 21:31

I'm in from the cold now so I'll have a crack at this little lot tomorrow afternoon.

I can't recall whether the buzzer sounded or not to be honest, I'll pay more attention next time.

My car is a '98, I looked in the handbook and Fuse 7 does tally with dash lighting.

I've been checking for continuity in the BLACK/RED wire with no luck but it might be that my colour guessing luck has run out. Whilst doing this though I took apart the smaller of the two multi-way connectors under the helmet holder and as I did so a relatively thick wire came away from it's crimped contact. So whether this contact is the culprit or not it will force me to pull test each and every wire to make I have no issues lurking.

Thanks again for you advice and suggestions.

Ian

[gruffalo]

billybradshaw said:

Right then, the little ones are tucked up in bed so I'll go and check for continuity.

Any thoughts on the blummin' MIL and handbrake lights? I'll stick my DVM directly to them and see if they illuminate to at least rule out knackered LEDs.

Cheers

Ian

There is a tiny fuse on the instrument PCB if that has blown you lose the buzzer and warning lights, I think it is rated at 0.5Amp.

[billybradshaw]

gruffalo said:

There is a tiny fuse on the instrument PCB if that has blown you lose the buzzer and warning lights, I think it is rated at 0.5Amp.

OK great, some more good information. Is it an off the shelf fuse or a TVR special?

Ta

Ian

[gruffalo]

It is a little PCB surface mount fuse best fixed by soldering a bit of fuse wire across it.


http://www.pistonheads.com/gassing/topic.asp?t=910...

Edited by gruffalo on Friday 4th March 10:22

[billybradshaw]

gruffalo said:

It is a little PCB surface mount fuse best fixed by soldering a bit of fuse wire across it.


http://www.pistonheads.com/gassing/topic.asp?t=910...

Edited by gruffalo on Friday 4th March 10:22

Right then, next update:

Issue 1: No Brake warning or MIL light

The pico fuse is indeed no more. When bypassed the brake warning light illuminates. Still no MIL light.

Issue 2 Ignition cut off

I've belled out the wire all the way from the IGN module back to the switch and I'm pretty sure now that the switch is knackered. What's the easiest way to remove the offending article?

(Switch now ordered from RS)

Thanks to you guys I'm getting there.

Cheers

Ian

Edited by billybradshaw on Friday 4th March 17:05

[tofts]

Ahh yes the fuse. Good call. Nor certain on MIL. Will be at the car shortly so will have a quick look at the board as dash is out atm.