Hi all,
Having an issue with my 1987 318i M10 E30.
When I turn the key of the ignition to the off position with the motor running the revcounter needle climbs then drops off to zero. This has happened a few times now which causes the vehicle to be unable to turn over/start on the next crank. I have installed a switch in line which turns the starter over when this happens but yesterday it would not crank over and only switched the internal fan on.
I assume that there is a possible short somewhere but don't know if the issue above is related.
No work has been done to any electrical cable/component except the wiring of the switch.
All advice would be grateful as this is my only ride.
Thanks
Possible electrical short!?
Moderator: martauto
-
Brianmoooore
- E30 Zone Team Member
- Posts: 49360
- Joined: Mon Jan 10, 2005 11:00 pm
I very much doubt that your two faults are related.
You almost certainly have an instrument cluster fitted with a SI board with Lithium batteries, and these tend to commonly develop the fault you describe with the tacho. AFAIK, the fault has no effect when the car is running, or any other effects when it is switched off.
There are more than one possibilities with the cranking fault, and the first thing that should be tried, when the problem next occurs, is to see if the engine will crank by shorting together the appropriate two pins in the diagnostic socket. (See wiki.)
Is/was the car a manual or auto gearbox?
You almost certainly have an instrument cluster fitted with a SI board with Lithium batteries, and these tend to commonly develop the fault you describe with the tacho. AFAIK, the fault has no effect when the car is running, or any other effects when it is switched off.
There are more than one possibilities with the cranking fault, and the first thing that should be tried, when the problem next occurs, is to see if the engine will crank by shorting together the appropriate two pins in the diagnostic socket. (See wiki.)
Is/was the car a manual or auto gearbox?
-
CFS318
- E30 Zone Newbie
- Posts: 15
- Joined: Fri Jan 13, 2012 11:00 pm
Hi Brian,
Thanks for the info.
Do you think replacement of the SI board batteries would solve the tacho problem?
The car is manual and shorting pins 11 and 14 on the diagnostics socket does crank the engine.
Thanks for the info.
Do you think replacement of the SI board batteries would solve the tacho problem?
The car is manual and shorting pins 11 and 14 on the diagnostics socket does crank the engine.
-
Brianmoooore
- E30 Zone Team Member
- Posts: 49360
- Joined: Mon Jan 10, 2005 11:00 pm
I don't think new batteries would help - the circuitry around the batteries is very different from that on boards with NiCd batteries, and the batteries serve a different purpose. It's just something that happens to this version of the board, but doesn't have any effect other than looking a bit odd.
The cranking problem appears to be with the car body part of the loom, and could be a faulty ignition switch, the connector between the ignition switch wiring and the body loom not pushed together properly (should be clipped to the steering column, about half way down), the connector above the glovebox area not pushed together (unlikely), or a faulty immobiliser (not necessarily one you know about) connected into the start signal wire.
The wire you are looking for is black at the ignition switch, but changes to black/yellow for the rest of the way.
The cranking problem appears to be with the car body part of the loom, and could be a faulty ignition switch, the connector between the ignition switch wiring and the body loom not pushed together properly (should be clipped to the steering column, about half way down), the connector above the glovebox area not pushed together (unlikely), or a faulty immobiliser (not necessarily one you know about) connected into the start signal wire.
The wire you are looking for is black at the ignition switch, but changes to black/yellow for the rest of the way.