gr8-wht

Anyone have any idea why the left rear turn signal will not work on a '89 928? I'v already swapped the relay and bulb with new ones, checked the fuse, I have voltage at the fuse not at bulb connecter and measured 22.6 ohms on the ground wire. Bulb will not work on the left side although it works on right.

The Forgotten On

Your resistance sounds high. Clean all of the ground points and apply some deoxit to them along with some in the harness connectors.

Inspect the bulb harness for any signs of burning due to the bulb getting hot and replace it if necessary.

Alan

Resistance on ground is way way too high here - it must be << 1 ohm - close to 0.

This is your problem #1, however if you have no voltage at the socket alternating when flashing (without the bulb installed) - then you likely have another problem too. However start there and fix the ground problem first.

Alan

gr8-wht

I thought the resistance sounded high as well so i measured the working side. it measured 19-20 ohms (could be my meter i guess). I have power at the fuse, is there anything other than wire between the fuse and tail light?

Alan

You are doing something wrong... start out by changing the battery in the meter. How are you measuring this - bulb out? between bulb holder and what ground point?

From the fuses the wire goes all the way to the cluster connectors, you do have 4 fuses for turn signals:

Front Left #34
Rear Left #35
Front Right #36
Rear Right #37

So check #35 WITH A DMM (fuse out in circuit tester/ohms mode).

Then with fuse back in circuit - test the notch above the bottom terminal in voltmeter (to Ground) mode with flasher operating - do you see changing voltage there?

Alan

gr8-wht

Okay, I changed the battery in the meter. From the tail light disconnect (looks like pin 3) to the spare tire grounding point I'm now showing 1.6 ohm.

Alan

Still seems far too high. A turn signal bulb is 21W so that is approx 6.8ohms when operating (hot). If your ground has 1.5 ohms then you will be dropping about 2.5v on the ground wire alone and the light will be very dim.

Either you meter doesn't measure low resistances very well - or you still have a ground problem. If other lights illuminate fine and you tested the main incoming ground - seems your meter is suspect.

Test the fuse side next.

Alan

gr8-wht

Alan, Thanks for helping me through this problem. Today I used a test probe at the fuse and found that the top half caused the probe to flash. Thinking that the bottom half should send to the tail light, I connected a wire to the bottom half of the fuse box connection point and stretched it to the back so i could meter the resistance on the "power" side and it's resistance was less than the ground side. Replaced the fuse and still nothing. made a jumper to use in place of the fuse and bingo, tail light flashes. At the start of this I metered the old fuse and even swapped it with a known working fuse and nothing. Now it looks like I have to figure a way to tighten the connection at the bottom half of the fuse box connection point to the fuse. Thanks again.

Alan

NO !! take it out and never EVER do that again!!!

This is one of the stupidest things you can ever do to your car and can easily ruin your wiring harnesses somewhere in the middle (!). Never replace fuses with higher amp fuses and never replace with a jumper either (unless the jumper has the right fuse in it).

Sorry to be blunt - but this is truly for your own benefit.

If you can't restrain yourself from stuff like this - just have a 'professional' work on your car.

You could have accomplished the same thing safely with a DMM - test between the fuse lower contact (dimple) and the CE panel pin to see if they actually make contact.

Alan

Kevin in Atlanta

A fellow owner chased the same issue and ended up being the fuse was not making good contact. Sounds like the same thing here. I had the same issue with a dodgy hatch release not cycling. Turned out to be the 1 amp fuse. I bent the fuse contacts in opposite ways and hatch release cycles and stops.