Green Digital Dash Not Working

[romanf]

when I said "very clever people" I meant Michael and here he is. If he can't fix it not many people can.

[DGUN]

Well thanks again Amanda, for coming over again and trying the dimmer switch replacement, which unfortunately did not work. So now we have ruled out the dash itself, the fuses, the dimmer switch and the relief relay. Not sure what else there is left to do, other than the ignition switch, which someone suggested? Unless of course it is a combination of the above....... as always any more ideas greatfully received.

[JimH]

Originally Posted by DGUN

Well thanks again Amanda, for coming over again and trying the dimmer switch replacement, which unfortunately did not work. So now we have ruled out the dash itself, the fuses, the dimmer switch and the relief relay. Not sure what else there is left to do, other than the ignition switch, which someone suggested? Unless of course it is a combination of the above....... as always any more ideas greatfully received.

Did you try a relief relay from a working car? Or just clean up yours externally? If not already done, I'd try that, then try replacing the ignition switch (cheap enough).

What you really need to do is determine which of the supply Voltages is actually missing - otherwise, you're just stabbing in the dark and replacing bits...

[PeterB]

Originally Posted by JimH

Did you try a relief relay from a working car? Or just clean up yours externally? If not already done, I'd try that, then try replacing the ignition switch (cheap enough).

What you really need to do is determine which of the supply Voltages is actually missing - otherwise, you're just stabbing in the dark and replacing bits...

Yep, we tried mine Jim. Still no joy. So it's not the fuse, dimmer switch or relief relay.
It's getting power to the warning lights in the dash, just not the main display.

Limited to what we could find without a multimeter or the like though unfortunately. An ignition switch is cheap and easy enough to replace, and worth doing anyway.

[Nihilist]

When you have a multimeter, try measuring the voltages on the PSU to
ground. You should have -22, -7 on the output lines - maybe the fault is there
if those voltages are missing. Also you should see +12 on the input line.

Cheers, Michael

[DGUN]

Originally Posted by PeterB

Yep, we tried mine Jim. Still no joy. So it's not the fuse, dimmer switch or relief relay.
It's getting power to the warning lights in the dash, just not the main display.

Limited to what we could find without a multimeter or the like though unfortunately. An ignition switch is cheap and easy enough to replace, and worth doing anyway.

I have since replaced all of the fuses and still no luck. I have just noticed that if I press the 'R' buttom on the computer, and keep it pressed that the time does light up. Does that provide any further clues or point to anything in particular?

[Nihilist]

Yer, that helps. That shows that the power supply works. If the dash does not
"power up" on ignition, the processor could be the cause for the misbehaviour.

Cheers, Michael

[s2martyn]

any joy with this??i have the same fault

[Ian Simmonds]

Originally Posted by DGUN

I have since replaced all of the fuses and still no luck. I have just noticed that if I press the 'R' buttom on the computer, and keep it pressed that the time does light up. Does that provide any further clues or point to anything in particular?

I bet, If you back feed it it'll work too...

with no key in the ignition...

turn the headlight switch to position 2 (dipped headlights), then hold the main beam flash, this should back feed No.5 relay and illuminate the dash.

[omigod]

Don't you just love these old cars.....

Mine has developed the same (similar) fault, fitted new battery (old one U/S) turned on ignition for the first time this year and the dash came up as normal, cranked engine and the dash went off (as it should i believe) when the engine stared the dash never came back on. Also lost heater fan, elec windows and possibly radio. If i press the R button i get a bit of response with some parts lighting up.
My money is on relay 5, is there another relay i can swap it with to test it out, the fuel pump relay has the same internal layout but is only rated at 25amp not the 70amp of relay 5 but is it safe to try if only for quick diagnostics.