strange fault

[Aussie John]

I fired the Griff up today and let it run through a few on/off cycles with the fans; on 2 occasions when the fans cut in the engine stalled but the ignition light went out with the key still in the run position. After maybe 30 seconds the ignition light was back on but the alarm was set, reset the alarm and the engine fired up ok, any thoughts? maybe the battery voltage dropped too low when the fans kicked in and stalled the engine this triggered the alarm, thanks for any help, cheers, John.

[griffdude]

Yes, I think you’re right. Is this on a PreCat? If so, my alternator isn’t triggered unless the rpms are raised a little. Maybe the fans kicked & dropped the battery output enough to stop the engine.

[Aussie John]

Hi Howard, it is a pre-serp with a 65amp Magneti Marelli alternator, it hasn't had this happen before but maybe the battery is a bit past its best, cheers, John.

[blaze_away]

As already said, its combination of low battery and alternator not throwing out much. Stick a volt meter on it, you should have 14 ish volts when engine is running.

[Aussie John]

Hi Frank, when the engine is running without the fans it shows 14v but when the fans cut in the voltage drops to 12v on idle. The battery voltage is 12.59v with nothing switched on but maybe not so good under load.

Edited by Aussie John on Tuesday 24th August 20:17

[Steve_D]

Spin your fans with your finger. If they are stiff they will be pulling to much current.

Steve

[Aussie John]

Thanks Steve, they were new fans about 18 months ago and spin ok now, maybe drawing more current than the old ones but this fault hasn't appeared until now, I will pull the battery and have a heavy load test done as a starter, cheers, John.

[blaze_away]

Could be the alternator, get it off and ask specialist to test it. Also a bad connection on earth points or battery and feed to fuse board. Disconnect them and clean and refit and smear with vaseline.

[Steve_D]

blaze_away said:

.................... Also a bad connection on earth points..............

And the worst earth point on our cars is?

The one on the front of the chassis where the fans earth.

Steve

[Aussie John]

A friend said he had a melted connection behind the dash where the wire from the alternator ran to the battery.[ 1993 griff 500] I didn't think this wire would have had joins in it, any clues guys?

[Aussie John]

The battery checked ok under load but I changed it anyway, I put the alternator in and although it had 14v output it needed repairing, put it back together and bingo, the voltage only drops to 13v with fans running, changed the relay for the ecu which strangely smoothed out a rough idle [I don't understand this ] hopefully now all ok, thanks for all the help PS the earths at the front were under the lower anti-roll bar mounting bracket, anyone else found this?

[Colin RedGriff]

Have you made sure all the earths are clean and tight?

I had an issue which would cause the engine to stall at random times but usually when hot. I found the two earths either side of the transmission were not tight (not loose but not tight) and the problem hasn't reoccured since.

Whenever anyone says they are having strange electrical issues I always think of earths. All sorts of weird things can happen when the earths are not good.

Earth points
Front of the lower o/s chassis rail
Inside the o/s wheel arch
Bellhousing
Top of the transmission tunnel (both sides under the carpet by the dash)
Behind the fuel tank.

[Griffo400]

Hi Aussie John

Yep, my 92 400 has all the earths under the ARB mount. I changed the ARB bushes but didn’t see the earths when I reassembled the mount and couldn’t figure out why the fans, windscreen wipers lights etc etc were doing weird things when I operated different switch’s.
This all pointed to an earth wiring fault.
It wasn’t until I looked through the wheel arch and saw all the earths hanging in mid air that I realised what was wrong. Just couldn’t see them from above.
It was amusing for a while though.