945 charge / earth / warning light prob

[bluebrickrick]

It had to happen ! on my way home from removing more bits from the donor 945 just after dark, I noticed lights dimming, radio erratic and ABS warning on intermittently. ended up stranded by the roadside after the battery voltage was down to about 7 volts and desperately trying to find why before the ignition finally died.

Large jump in time

RAC guy arrived and I ran through what I had and hadn't discovered, concluding alternator brushes or similar fault and please just tow me home as it was starting to rain, turns out he had run a 240 for many years and wanted to try to get me going restarts instantly after hooking his battery pack on, he does much the same as I did check wise but on a restart noticed none of the usual warning lights on with ignition on so goes back to the ignition connection on the alternator (which both of us had measured a seemingly sensible voltage on previously) and says if we had a bulb and holder we could try connecting elsewhere to eliminate the ignition - well just happened to have a sidelight bulb and holder so soon tried, at which the engine coughed and the driving lights brightened but still no warning lights on the dash.

He made the clip connected jump lead a bit more robust and followed me almost home, charging fine at 13.9 volts everything else apparently working bar the dash warning lights, my guess is loss of earth somewhere and something may have back fed to another earth point via a fuse so that will be first stop in the morning, closely followed by a meander through the relays, but any suggested causes or cures for a similar occurrence gratefully received.

Unfortunate, but it was at one of the few places 2 cars could pass comfortably on my trip back and an RAC guy of the right vintage with 240 experience has to be Karma readjusting, plus he was less than the anticipated 90 minutes arriving - could have been a young lad who might still be scratching his head as to where his compooter should plug in

You'd have thought that having seen what I had just been doing to one her sisters with crowbar and angle grinder, the old girl might have resisted the temptation to misbehave for a while !

[TonyS9]

You sound like you know what you are doing but to clarify a common problem..

When using the meter you should always measure across the item you are checking, not relative to the chassis. Eg the alternator or battery. This will tell you if the voltage is truely correct, or volt drops can then be investigated on either + or - sides.

The connections on these old cars are becomming more corroded, I've developed several techniques to repair the cables (rather than replace). Mainly this is making fresh uncorroded surface to solder to.

[Laird Scooby]

Originally Posted by TonyS9

You sound like you know what you are doing but to clarify a common problem..

When using the meter you should always measure across the item you are checking, not relative to the chassis. Eg the alternator or battery. This will tell you if the voltage is truely correct, or volt drops can then be investigated on either + or - sides.

The connections on these old cars are becomming more corroded, I've developed several techniques to repair the cables (rather than replace). Mainly this is making fresh uncorroded surface to solder to.

In addition to measuring on the item as Tony suggests, you also need to measure from the terminals on the tiem to chassis and battery earths to ensure there isn't something strange happening. This will also indicate a possible fault area.

However, there's a good clue in the lack of instrument illumination. Two clues in fact. First points to the earth point in the drivers kick panel area, remove the trim and you should find it easily.

Next clue is the fact the warning lights came on sporadically. Remove the field wire (the warning light wire) from the back of the alternator, take it to earth using a piece of wire and switch the ignition on to position 2 without starting the car. This should bring up the charge warning light and the ABS, low washer fluid and a couple of other rarely seen warning lights in addition to the oil pressure warning light.

If so and removing the link wire and refitting it to the alternator doesn't immediately bring the charge and other associated warning lights on, there's a high chance the brushes are worn. Best way of buying them is with the voltage regulator but check the part number on the old one begfore doing so, there are two different regulators fitted to the Bosch alternator, one for 28mm and the other for 32mm slip rings. Doesn't sound much but you can't fit a voltage reg for a 28mm slip ring to the alternators with a 32mm slip ring. You can do it the other way round but it won't be long and you'll need to do it again as the brushes won't be long enough to reach once they have a small amount of wear on them.

Good news is the voltage regs aren't expensive, not worth using a secondhand one as you'll need to do the job again soon and a secondhand one may wear the slip rings abnormally involving a lot more work!

Have a practice run at removing/refitting the voltage reg, usually it's just two slotted screws and will give you the chance to see the brushes (or remains of!) and using your dentists mirror, inspect the slip rings. If they are severely worn, visit your parts mule and use the alternator from that, providing of course it's a similar or higher output in Amps.

https://www.ebay.co.uk/sch/i.html?_f...lator&_sacat=0

A few there to choose from, yours should have a rating of 14V (might be listed on fleabay as 12V but the rated output of Bosch alternators is 14V/xxA the xx denoting the output current) but the main thing is the part number of the voltage reg. If you can't find it, if you find the part number of the alternator (the Bosch number) which should start "0 120" i can cross-check which regulator you need.

[bluebrickrick]

Thanks both, haven't made a start on it yet as my ankle is revolting (!) against the treatment it received yesterday.

The usual warning lights bulb test display at switch on is not happening but it was charging well against full beam on the way home.

Was wondering overnight Dave if the start position key contact possible problem might be wider than just that position, although I'd not noticed warning lights unlit when the failure for solenoid to pull in occurs - I got the whole steering column / lock / switch barrel assembly out yesterday so can reverse engineer that.

May not get too far today with the ankle protesting but ought to be able to check / clean that earth star point along with checking out fuses and relays, at least there are blue skies to work under, despite being distinctly chilly.

Cheers, Rick

[Laird Scooby]

Originally Posted by bluebrickrick

Thanks both, haven't made a start on it yet as my ankle is revolting (!) against the treatment it received yesterday.

The usual warning lights bulb test display at switch on is not happening but it was charging well against full beam on the way home.

Was wondering overnight Dave if the start position key contact possible problem might be wider than just that position, although I'd not noticed warning lights unlit when the failure for solenoid to pull in occurs - I got the whole steering column / lock / switch barrel assembly out yesterday so can reverse engineer that.

May not get too far today with the ankle protesting but ought to be able to check / clean that earth star point along with checking out fuses and relays, at least there are blue skies to work under, despite being distinctly chilly.

Cheers, Rick

If the earth point is the same as mine Rick, it's a bank of male 1/4" spades, not a star "MEP". It may also be your instrument cluster is suffering a failure of the PCB on the back - without the ignition feed coming in the charge warning light won't work (nor will the others that are linked to it when not charging) and the speedo likely won't work, nor will the instrument dimmer.

Could be you hae several symptoms of just one fault, poor solder joints on the PCB on the back of your existing cluster.

[bluebrickrick]

OK Dave, electrical star point (regardless of connector) we are talking the same one just down from the bonnet release

Instrument illumination is as normal and dimmable, clocks other than speedo (which has Yacky-dacky rot) all working and seat belt and iirc handbrake warnings illuminated, the rest as one of my Japanese customers described a PLC problem 'all the little red lights become darked'

I'm going outside, I may be some time..............

Rick

[Laird Scooby]

Originally Posted by bluebrickrick

OK Dave, electrical star point (regardless of connector) we are talking the same one just down from the bonnet release

Instrument illumination is as normal and dimmable, clocks other than speedo (which has Yacky-dacky rot) all working and seat belt and iirc handbrake warnings illuminated, the rest as one of my Japanese customers described a PLC problem 'all the little red lights become darked'

I'm going outside, I may be some time..............

Rick

Didn't realise you were using the star-point term generically Rick, not to worry.

With that extra information, i'd start by replacing the ingnition/starter switch and then seeing what was left to sort out. It's the most likely cause of all the problems and you could end up chasing your tail somewhat hunting for bad earths that don't exist.

[bluebrickrick]

Story so far

All ashtray fuses OK
All ashtray relays removed, corrosion checked and replaced

No change

Under steering trim removed, ignition switch removed and no obvious problems
earthing point behind ECU spades removed & checked, all nice and clean

No change

Donor steering shaft / lock wangled across transmission tunnel and ignition plug attached (need to remove instruments as I couldn't get to the switch screws from below and I do not know, given Dave's warning, if it is the same switch as the donor)

Functions as original, no change to the problem.

I shall have to get close up and personal with the green book tonight, the closest to 1991 I have is dated 1994 - for something this fundamental ought I to be able to rely on wire colours / terminal no's or is there somewhere I can download an earlier one ??

The thick plottens with the RAC guy being so insistent that we have a bulb in the 'hot wire' could it be as simple as the ignition bulb on the dash blown ? can't believe they would compromise the reliability of a Brick with such a weak link.

I've just watched the string of Mr Musks satellites go over - lost count at a couple of dozen once I'd used up all available fingers and toes.......

Rick

[Laird Scooby]

Remember my test above with the jumper wire on the field/warning light wire from the back of the alternator Rick? That proves the circuit and the bulb.

If it doesn't light, then the bulb is blown. Check the rating on it as well, i doubt it's a 1.2W jobby like the rest of the bulbs in the warning lights.

[taiwan740]

Originally Posted by bluebrickrick

Story so far

All ashtray fuses OK
All ashtray relays removed, corrosion checked and replaced

No change

Under steering trim removed, ignition switch removed and no obvious problems
earthing point behind ECU spades removed & checked, all nice and clean

No change

Donor steering shaft / lock wangled across transmission tunnel and ignition plug attached (need to remove instruments as I couldn't get to the switch screws from below and I do not know, given Dave's warning, if it is the same switch as the donor)

Functions as original, no change to the problem.

I shall have to get close up and personal with the green book tonight, the closest to 1991 I have is dated 1994 - for something this fundamental ought I to be able to rely on wire colours / terminal no's or is there somewhere I can download an earlier one ??

The thick plottens with the RAC guy being so insistent that we have a bulb in the 'hot wire' could it be as simple as the ignition bulb on the dash blown ? can't believe they would compromise the reliability of a Brick with such a weak link.

I've just watched the string of Mr Musks satellites go over - lost count at a couple of dozen once I'd used up all available fingers and toes.......

Rick

Check the back of the dash - if the cable has come out then the alternator will not charge. Seriously, it's a total head****.

I had this before when I took the speedo and everything out to give it the hairdryer treatment - when I put it back in, a small cable managed to come out - this was for the battery light. This battery light leads to the D+ terminal on the alternator, and the alternator will not charge without it.

Totally **** and stupid design if you ask me. I took it to a few friends who couldn't spot the issue either, the alternator had continuity with everything, but refused to charge, replaced the alternator, still same thing. Turned out to be that bloody lead.

So yeah, if your battery light bulb is not working or not connected, then your alternator will NOT charge.