C4Betts

I've reviewed the electrical diagram for the turn signals to identify 'suspects' for the fuse to keep blowing and see only bulbs that may be the culprit. Its an 89 automatic.

Turn signals work for a 'while' (few minutes maybe) then the fuse blows.

This car has been sitting for years and this is the last thing I need to repair to get it on the road.

Flashers work fine and are on a separate fuse so I'm discounting the bulbs as the cause since the flashers work all the lights with no problems to date.

Has anybody had the problem too? Is it something in the column/turn switch stalk that is a common problem area for this?

Back up lights are in this circuit too but I can just leave it in park (never activating the backup lights) and the fuse will still blow.

Thank you for any help!

JackDidley

Could be a naked wire in the column. I had to replace a wire in mine that actually broke. Cut near both ends, fish a new wire down the column and solder the ends. Sort of hard to solder, reaching up under the dash but its possible. Used heat shrink too.

C4Betts

Thanks. That is I believe where I'm headed since it seems to blow randomly with now action going on... Most likely the hot wire to the turn switch/stalk...

My back is still hurting from getting under the passenger dash to find the turn flasher...

JackDidley

Mine would only act up with the column tilted down. You may try driving with the wheel in a different position to see what happens.

C4Betts

Looks like I'm getting confirmation of what I suspected anyway. Wire in the column is probably the problem...

Thanks!

pcolt94

It sounds like you have replaced the flasher already which is the first thing I might do.

If the car is static and not moving and the turn signals work and then the fuse blows, it seems like too much current draw when it's operating. If it was a shorted wire to ground, I would think it would blow almost right away. But would depend on the current it's drawing in reguard to the fuse rating.

Can you determine if one side blows it but the other side is OK?

Are you using the correct fuse amperage?

This is how I would attack this problem. I would install an ammeter in place of the fuse so I could monitor the current. Then you can see exactly what is going on. You can see if the current jumps if something is moved or if left and right sides are drawing the same amount of current. Then you can target in on the cause methodically.

Although not common, I have seen bulbs draw excess current but still work.

M. Schumacher

Corrosion in the bulb socket, or bare wires leading the bulb sockets are a possibility.

C4Betts

I rigged up a fuse 'extension cord' by taking a blown fuse, soldering a long wire to each of the now separate spades in the fuse plastic holder and put a 10 amp fuse at the other end of the wires to hold in my hand.

The turn signal / back up light fuse was blowing randomly - sometimes right away and some times several minutes into a drive.

I was able to detect the exact incident when it would blow. Made a noise too. It only happened when shifting through reverse which said it was the backup circuit. I can only guess that the 15 amp fuse could take the hit more times than the 10 amp I used for testing.

The backup lights on each side of the car - not the ones on each side of the license plate - but the ones on the quarter sides - have chaffed wires and the hot lead was actually shorting to the ground lead it is adjacent to. Both sides were like this. they are exposed to the elements so I guess this is what led to the chaffing...

Problem solved. I'm glad I didn't have to pull the steering column apart!

pcolt94

Nice creative troubleshooting.

Good work.

Arnold10

Trying to track down this problem. Don't want to take the steering column apart unless necessary.
If I turn on the ignition switch the signal fuse blows immediately. Hazards work fine.
I have disconnected the two connectors under the column which contain the turn signal switch wiring. Pic available if needed. Fuse still blows as soon as ignition turned on.
Based upon the wiring diagram I have it seems power is fed to the column via the white wire on the disconnected connector. If so, then the fuse should not blow. Am I misunderstanding the source of power?

VikingTrad3r

on my 87, the ctsy fuse was connected to my tail lights and many other things, and the light plug was shorted somehow. the second i turned the car on, it shorted, sending full 12v and full amos through the fuse and blew the fuse.

you will have a similar situation somewhere. find all the parts connected to the fuse you are blowing and look for chaffed exposed wires that are shorting. if u have removed the turn signal lever harness and it still shorts i see no reason to pull the wheel aprt.

hcbph

Maybe I'm too old-school here but I wouldn't care to tear down a steering column or similar without knowing for sure that's where a problem is. Personally if it was me, I'm get the schematic out of the fsm, unhook the connector at the bottom of the column along with the battery. Jack up the front end and with it supported, turn on the key and with an ohm meter hooked up to the connectors going into the column for the turn signals wire (one side at a time, other to ground) I'd work the heck out of it all the while watching for any indication it's going to ground.

I'd test as much of the wiring that first before spending a lot of time or money on things that 'might' but 'might not' be the cause.

Might not find it that way, but then again you might.

WVZR-1

I believe you likely have an issue with BACK UP LAMPS - they're fused with the TURN LAMPS. With the directional defeated and it seems you likely do then I'd say that's the go to point.

I'm not familiar with any WHITE to the TURN SWITCH other than the wire from the stop light switch. You say HAZARDS work and STOP/HAZARDS are on the same fuse.

Is this car an A4 or a 4+ MT?

xrav22

I would start by cleaning all the sockets and putting some dielectric grease in each. If the car has been sitting you have to do that anyways I know I did just to get them to work. I also replaced every lamp in the car.

Arnold10

Thanks for the updates folks. Let me address each one of you one at a time in this post then I'll add todays update.

VikingTrad3r - I think I understand your comment. Question, if I have the connectors on the column disconnected would the light sockets, turn, brake, hazard be a consideration? The wiring diagram shows everything goes through the steering column switches and all of that is disconnected.

hcbph - Agree with you here this is typically how I troubleshoot circuits. If the car wasn't so hard to get into and find wiring I might not be troubling anyone here with thoughts and suggestions, but as you might guess I don't want to disassemble anything unnecessary, things tend to break, other problems appear.

WVZR-1 - Same question I posted to Viking. If the column is disconnected, the shifter in park, the hazard of course now non-functional since I disconnected the column, any potential short in the sockets or the tail wiring would not be relevant would it? My wiring diagram is from a Chiltons and is decent but does not go into details such as where connectors are, how many there are. To you question it is an Automatic 4 speed.


xrav22 - Same question as to WVZR-1 and VikingTrad3r. If I have these things disconnected I don't think the lighting wiring or the sockets could have an effect on my current symptom.


Now as to my current status.

Today I removed the status panel above the radio. Directly behind it are several fuses (theft etc) and a couple of the relay units, blinkers and I assume hazard to the left of it. I can supply pictures of each area if desired, either directly into a post or I can upload to google and provide links.


I removed the flasher unit for the blinkers, put in a new fuse and turned the ignition switch. Fuse popped immediately.
In theory my mind says the wiring from the fuse block to the flasher unit is shorted to ground somewhere along the way. Any comments or thoughts on my current assumption?

Here are my detailed updates:

Fuse block: Left side has 13V, Right side 0. Is as it should be since no fuse installed.
Fuse block continuity: Right side zero ohms to flasher unit green wire. Believe as should be.
Fuse block right side to battery ground. Shorted.....remember no flasher unit and no steering blocks connected.
Flasher green lead to battery ground. Shorted....
This seems to indicate the green wire somehow has developed a short to ground. ?Thoughts? ?Contradictions?

Finally, this to me seems to state I must get behind the right passenger panel to the fuse block which seems to be riveted into the car and reach that green wire. cut and replace with a new wire to the flasher unit?

Am I being stupid? Am I missing something unique to this car?

Again I can provide picture with more details of steps taken if desired or if you think it will help picture what I am talking about.

WVZR-1

NO - with shifter in PARK and the cable working you can only assume the car "ain't gonna roll off". You've accomplished nothing towards diagnosing the BU circuit that's also "fused" along with the directionals.

Arnold10

[QUOTE=WVZR-1;1592498295]NO - with shifter in PARK and the cable working you can only assume the car "ain't gonna roll off". You've accomplished nothing towards diagnosing the BU circuit that's also "fused" along with

Thanks, I will see if I can find where the two circuits could be attached and look at that as a possibility before tearing the rest of the dash apart. I would hate to replace that wire only find a short still exists.

Hooked on Vettes

Strange some of the the wire colors you mention don't match the factory schematics.

Here are the schematics.

Should be a Dark Blue wire from the Turn/Backup fuse that goes to the turn signal flasher and the Park/Neutral transmission position switch.

Most likely the Dark Blue wire going to the Park/Neutral transmission switch is shorting somewhere under the center console.

Arnold10

Hooked on Vettes and other posters.

Thanks again for the information. "Hooked" your drawing is much clearer than the one I have been using.

Yes, the colors did not match and it was my fault. As we were taking things apart, blame it on heat, impatience, whatever I did a dumb sh** thing and took out the horn relay, not the signal flasher unit.

I snapped pictures of the schematics over the weekend and took time to sit down and review them in more details and figured out I screwed up. We have not had time to get back to the car to continue diagnosis, but the first thing will be to track down the signal flasher wherever it is hidden in this mess called a wiring harness.

You and others have helped greatly in calling out that the backup circuit is linked and the wiring colors I called out did not match.
The diagram we have again was unreadable for colors until I snapped the picture and zoomed in and the car itself the fuse block only lists turn signals and you cannot see the word backup.

So hopefully next week we will get time to look at the car in a fresh light and not in haste or heat.




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Hooked on Vettes

The turn signal flasher is located above the passenger side foot well. If you lay on your back and look up it's to the right of the ECM towards the transmission tunnel. You can unplug the ECM which is the large metal box and remove it by removing the two 3/8 bolts holding the retainer bracket. You should remove the negative battery terminal if you do unplug the ECM harness to get it out of the way.