Half the car is dead :-(

[Juddder]

So I have a strange scenario where after my recent fusebox self implosion that now half the car (the part that drives it largely) refuses to work and the starter motor is stuck on so wondered if anyone had ideas as to where to look next?

What does work (basically all the bits that should work with the car turned off):

- Alarm enable / disable with indicators flashing and beeps
- Head lights
- Hazard lights
- Horn
- Boot lock when Door ECU connected (you can hear the solenoid shut when the alarm arms)

What doesn't work

- Fuel pump
- Radio
- Indicators
- Doors
- Windows
- Heaters

What runs all the time
- Starter motor

My fusebox is one of those that has no fuse in position 13, and when I did accidentally put one in there as I thought that might be the problem, on enabling the car the starter motor runs continuously but no fuel pump, so luckily the car doesn't try and drive itself!

I checked an older photo and my car should have a 20 Amp fuse at position 13 so I have re-added one and now the starter motor just runs continually

My next plan is to test every fuse, but just wondered from experience if others have gone through similar troubles and if so where best to look? The alarm potentially?

I've just tested every fuse and a 15 Amp at position 7 was blown so I replace that but it hasn't made any difference

Many thanks Alex

Edited by Juddder on Wednesday 10th November 14:29

Edited by Juddder on Wednesday 10th November 14:43

[southendpier]

have you checked the control boxes on the shelf in the boot to see if any have cooked themselves? Take out the plugs and you may see "burns"
I have this on mine (door control iirc) and all sorts of other problems happened.

[Juddder]

So I managed to get an auto-electrician to look at the fuse box today and it turns out that I had connected the single red wire that had fallen off the back of the fuse box when it fell into the wheel arch to the wrong connector on the fusebox

On the photo below I had it connected to the blade connector on the left labelled 'S' whereas the electrician noticed that the bottom blade connector that it is now connected to had live power, so his suggestion was to move the wire to that connector instead, and when we did this we made progress.

So with the wire correctly connected, the starter motor no longer continually runs and the steering wheel start / stop buttons work correctly and we can start and get the car running, which is great progress

However I still have no doors or windows, and the left indicator flashes continually and the washer pump runs during startup so there are still more gremlins to investigate!

I'm thinking of buying a spare Indicator Control Unit from one of the usual sources to test this out to see if it helps, and maybe sending the door ECU off to get it repaired - I think HF Solutions used to be the place to send them to?

[TwinKam]

But don't let Penelope see that crimp!

[Byker28i]

Hopefully you haven't blown anything. Now you've got things working, have you tried disconnecting the door control box, leave it a bit and reconnect just to reset things? Last time I changed the battery I had to reset mine, then reset it again because the windows wouldn't wind up etc.

[Juddder]

Byker28i said:

Hopefully you haven't blown anything. Now you've got things working, have you tried disconnecting the door control box, leave it a bit and reconnect just to reset things? Last time I changed the battery I had to reset mine, then reset it again because the windows wouldn't wind up etc.

Thanks for the advice and the support and yes definitely much better to have a driveable car that at least I can then fix the other gremlins with!

Out of interest for my future self I found this post from 2006 which also talks about the strange behaviour where the starter motor engages continually - in their case it was from removing a fuse but I'm guessing the wire had disconnected is part of the same circuit to have had the same effect

"There are several different fuse boxes out there in Cerberas.

One of the fuses on ours, if removed, just starts the starter motor over and over and over and over... we thankfully found out with the car in neutral!

Someones already mentioned my personal fave fuse... the one which connects the radio, drivers door lock, boot lock (handy), hazards, wipers and who knows what else. Fun."

On the doors and windows I have unplugged the door control unit and will leave it like that for a few days and then reconnect it to see if it makes a positive difference

There is also another one of the control boxes - to the right of the door control unit in this photo - that has a loose bottom and corrosion on the bottom of the PCB but isn't labelled so I was thinking of unplugging that and soldering the dry joints - does anyone know what it does before I start?

[Byker28i]

I think the first time I tried using the cigarette lighter socket for power it blew the fuse, which took out the radio, drivers door etc...

My boxes on the rear tank are:











So looks like the wonderfully titled 12VHP/2

[Juddder]

Awesome - thanks for the photos and they'll be really handy for everyone else too

So I studied the wiring diagrams and found that there are only two units on that that have 6 wire connections - one is the cryptically labelled 'Alarm Accessory' and the other is labelled 'Dim Dip Unit-ECU'

From studying your photo and the colours of the wires it looks like it is the 'Dim Dip Unit-ECU' as the colours are

1 - G (Green)
2 - U/W (Blue with White) [traced from 'Dim Dip Control Unit-ECU']
3 - R (Red)
4 - B (Black)
5 - R/W (Red with White)
6 - R/B (Red with Black) [traced from 'Dim Dip Control Unit-ECU']





Quite why the car needs two ECU boxes for the dim dip in the lights I have no idea but at least we now know what it is meant to do!

[LLantrisant]

my Door/Window ECU was repaired in 2018 by Python racing.

i found a sticker (hand written) near the red-highlighted connector saying "plug-in last"

[TwinKam]

Looks like the power supply only on that plug, so that makes sense...

[Juddder]

TwinKam said:

Looks like the power supply only on that plug, so that makes sense...

Good tip and yes it is, it's J46 - as part of my investigation task I've been documenting all of the ECU / Control Box wiring and that plug is just +12V and Gnd

I'll create a new post at the end of this and post them all up - hopefully get it stickied and then it can be a reference for everyone

3. Door Control - ECU

J47 -J48-

J46 J45

(J45) door ECU conn 1

A1 - RH Pin Switch (W/P)
A2 - Lock Switch (S/W)
A3 - RH Inner Switch (O/W)
A4 - LH Inner Switch (O/W)
-
A6 - LH Outer Switch (O)
A7 - RH Outer Switch (O)
A8 - Boot Switch (B/R)
A9 - N/C
B1 - LH Pin Switch (W/P)
B2 - RH Window Position (U/V)
B3 - Alarm Input (K)
B4 - LH Window Position ?
B5 - RH Window Down (Y/G)
B6 - LH Window Up (R/B)
B7 - LH Window Down (R/G)
B8 - RH Window Up (Y/B)
B9 - Road Speed (S)

(J46) door ECU conn 2

A1 - Earth (B)
A2 - N/C
-
A4 - Battery (R)
A5 - N/C
B1 - N/C
B2 - N/C
B3 - N/C
B4 - N/C
B5 - N/C

(J47) door ECU conn 3

A1 - Boot Lock Drive (R/V)
A2 - Battery (R)
-
A4 - Earth (B)
A5 - Battery (R)
B1 - Interior Lamp (P/R)
B2 - RH Lock Drive 1 (U/O)
B3 - RH Lock Drive 2 (U/G)
B4 - LH Lock Drive 1 (U/W)
B5 - LH Lock Drive 2 (U/V)

(J48) door ECU conn 4

[Front]

B1 B2 B3 B4 B5
A1 A2 A4 A5

A1 - Earth (B)
A2 - RH Window 1 (Y/B)
-
A4 - LH Window 1 (R/G)
A5 - Earth (B)
B1 - RH Window 2 (Y/G)
B2 - Battery (R)
B3 - LED Drive
B4 - Battery (R)
B5 - LH Window 2 (R/G)

[Penelope Stopit]

Juddder said:

Quite why the car needs two ECU boxes for the dim dip in the lights I have no idea but at least we now know what it is meant to do!

Could it be that

Dim Dip Control Unit does the switching

Dim Dip Unit contains a resistor that drops the voltage

Keeping the above control circuits apart is a good idea as the resistor gets hot

And

Circuit can be easily altered to allow the building of cars with and without dim dip

[Juddder]

Penelope Stopit said:

Keeping the above control circuits apart is a good idea as the resistor gets hot

Could be - how did you get on with your replacement circuit?

I quite like the idea of putting two of these fused relay boxes in the front wings and removing the rear boxes completely like @RichVr did in this thread or at least disabling the Dim/Dip like @alinton in this thread

[Penelope Stopit]

Did have a circuit in mind and as you'll have seen had sorted all the parts

Didn't draw and post the circuit as nobody was interested

Have put some time in today refreshing my brain and now have a circuit

The following will possibly give you some ideas, I do have a complete working diagram on paper but need some time to draw it

Should you want me to draw and post a full diagram I will gladly do so but will need a little time

Obviously side lights and fog lights circuits need sorting but they're easy

This circuit allows the removing and throwing away of all the light control units

Edited by Penelope Stopit on Thursday 18th November 08:48

[Juddder]

Penelope Stopit said:

The following will possibly give you some ideas, I do have a complete working diagram on paper but need some time to draw it

Should you want me to draw and post a full diagram I will gladly do so but will need a little time

Obviously side lights and fog lights circuits need sorting but they're easy

This circuit allows the removing and throwing away of all the light control units

Looks good and the latching relay for the full beam button is nice. re: circuit yes would be interested and thanks for the circuit above

On further investigation today I'm pretty sure I found out the reason my left indicator was stuck flashing

Looks like these are diodes that protect each of the 4 miniature 12V relays (feme vt a 001 12) in the indicator and hazards control box and one of them got friend when the fusebox fell - probably due to grounding or similar I would guess

I'm planning on unsoldering it and replacing it with a IN5817 diode which I have a few hanging around of - 3 lines on the circuit board indicate cathode so I can confirm the polarity even though it's fried

[Juddder]

and this shot of the circuit board layout confirms that - the diode in question is connected to pin B4 which is the LH Turn Signal

1. Indicator ECU (J55)

--------------------------------
| A1 A2 A3 A4 | | A6 A7 A8 A9 |
B1 B2 B3 B4 | B5 | B6 B7 B8 B9
------------------------------

A1 - RH Indicators (G/W)
A2 - Flasher Input (LTG/N)
A3 - LH Indicators (O/R)
A4 - N/C
-
A6 - Ignition (G)
A7 - Flash Power (G/Y)
A8 - Battery (R)
A9 - Hazard Signal (N/B)
B1 - RH Turn Signal (G/W)
B2 - N/C
B3 - N/C
B4 - LH Turn Signal (G/R)
B5 - N/C
B6 - N/C
B7 - N/C
B8 - N/C
B9 - Earth (B)

[Byker28i]

There's some really good pin outs etc coming out on this thread.
Alex, was it you that did the http://tvr-cerbera.co.uk/ with all the manuals and wiring diagrams on. Might be worth adding these?

I'll grab a copy as well...

[Juddder]

Byker28i said:

There's some really good pin outs etc coming out on this thread

Thanks - it's actually quite therapeutic documenting everything as you go, and seeing as I _have_ to as the car imploded it's electrics, I might as well share everything as I go

The TVR site isn't mine - I have the alternative parts list summary - but yes I will definitely post up a sticky post of all of the pinouts and diagrams when this is finished as it will be a good reference for everyone

So the indicators and hazards control box is basically made up of 4 micro relays, 6 diodes and some wire jumpers

Here's a shot of the bottom of the PCB with the diodes marked in pink, the relays in purple and the wire jumpers in blue - we can easily make a replacement from this as these boards are now pretty much unobtainium

[DuncanM]

I enjoy following all these auto electrical threads, sadly I don't know enough to contribute.

I'm thinking I need to do an auto electrical course because it's interesting, and will be incredibly beneficial as a Cerbera owner.

[Penelope Stopit]

Juddder said:

Penelope Stopit said:

The following will possibly give you some ideas, I do have a complete working diagram on paper but need some time to draw it

Should you want me to draw and post a full diagram I will gladly do so but will need a little time

Obviously side lights and fog lights circuits need sorting but they're easy

This circuit allows the removing and throwing away of all the light control units

Looks good and the latching relay for the full beam button is nice. re: circuit yes would be interested and thanks for the circuit above

On further investigation today I'm pretty sure I found out the reason my left indicator was stuck flashing

Looks like these are diodes that protect each of the 4 miniature 12V relays (feme vt a 001 12) in the indicator and hazards control box and one of them got friend when the fusebox fell - probably due to grounding or similar I would guess

I'm planning on unsoldering it and replacing it with a IN5817 diode which I have a few hanging around of - 3 lines on the circuit board indicate cathode so I can confirm the polarity even though it's fried

Looks a nice fix for the indicator problem

Am now waiting for a manufacturer to mail me the full specification of a relay, could take a day or two, can't go any further until then

Will be back soon