thedoc New Reader
4/15/19 3:21 p.m.

I have a 91 mustang that I just picked up.  I cannot get the turn signals to work.  I have established that there is no power at the fuse itself.  The flashers do work.  I only have a harbor freight multimeter.  What tools do I need to diagnose electrical problems and is there a  decent website that would teach me?  I am a decent basic mechanic but have always left electrical problems to the professionals.

I did put on the blower on my 06 mustang, but the installation manual was excellent, so I give that most of the credit.  I'm sick of not understanding this stuff and want to figure it out.  My wife is pushing me to take the car into the garage, I just want to figure it out myself.

I'm not sure which flag I'm waving, but I'm waving one!

Stampie PowerDork
4/15/19 3:23 p.m.

Is the fuse good?  I do a diode test (the beepy thing on the meter) to make sure. How did you test power to the fuse?

thedoc New Reader
4/15/19 3:54 p.m.

I just put the multimeter probes in.  I did not think about the beepy thing.  The car has aftermarket fast and furious headlight assemblies, but the wiring and ground to that look good.  

SEADave HalfDork
4/15/19 4:08 p.m.

The big multi-function stalk on foxbodies is a known problem area.  I had to replace the one on my 1990 as the headlights would only work intermittently.   Not a cheap part, you may get lucky at the local pic n pull.   

thedoc New Reader
4/15/19 5:06 p.m.

I put a new stalk into the car.  It did not change the problem AND if you pushed it up, the wipers wiped and the washer would squirt!  The old one is going back in!  It worked fine before, just did not work the turn signals.

Run_Away Dork
4/15/19 5:10 p.m.

You need a wiring diagram so you can check where that fuse receives it's power from.

bentwrench SuperDork
4/15/19 5:20 p.m.

Run Away has the answer.

dj06482 UltraDork
4/15/19 7:14 p.m.

Just sent you a PM, I have a factory service manual for a '92, and just took some pictures of the relevant sections. Do your 4 way flashers work (that should also engage your turn signals)?

Here's a link:

jfryjfry HalfDork
4/15/19 7:39 p.m.

I have no idea if this is relevant but my 72 bronco has separate flashers and somewhat separate wiring for signals vs flashers

Curtis UltimaDork
4/15/19 7:44 p.m.

It's also not unheard of for the flasher itself to die.  Do the 4-ways work?  Swap the flashers and see if the problem follows the flasher.  The turn signal flasher should be the one on the bottom.  Directly above it on the top of the fuse box is the other flasher for the 4-ways

Curtis UltimaDork
4/15/19 7:47 p.m.
thedoc said:

I just put the multimeter probes in. 

Did you put the probes on both sides of the fuse, or did you put one to ground?  If you try to test voltage across both sides of the fuse, it will say 0 volts even if there is 12v going to it.

thedoc New Reader
4/16/19 5:40 a.m.

In reply to Curtis :

Yup, I did it wrong.  I have a patient who is a mechanic.  He sometimes checks out cars/trucks before I buy them.  He brought me a wiring diagram and a light probe last night.  I have the day off and will mess with it today.  He is also going to loan me one of his old books on automotive electrics.  I'm determined to give this my best shot before I turn it over to someone else.. 

When I learned about cars, it was volkswagons, bug eyed sprites and mg midgets.  I also had a 48 plymouth that had one fuse and tubes in the radios.  No wonder I never had to learn this.  

thedoc New Reader
4/16/19 8:08 a.m.

In reply to dj06482 :

Wow, thanks for the link. I don't know how to look at a pm, or I just can't find it.  I am pouring over the diagram right now. I just found a connection not connected under the dash, but it looks like I have to take more apart to get them together.  

To answer your question, the four way flashers do work, but they flash the inner lights and not what I would expect to be the turn signals

thedoc New Reader
4/16/19 6:43 p.m.

Hey Gents,  I have a bad ignition module/actuator do-hickey.  I bought a new one, but I have to figure out how to get the factory star screws out.

I'll keep you posted, thanks

dj06482 UltraDork
4/16/19 9:36 p.m.

Ignition module is a common issue, I remember replacing it on one of my '92s. I can't remember the process, but I can probably look it up in the shop manual tomorrow.

thedoc New Reader
4/19/19 6:34 p.m.

Hey gang.  I replaced he ignition module.  I now have heater blower motor!  I have power to the fuse for the turn signals which I did not have before. I also do not have power to the turn signal flasher.  

?? What do y'all think?


thedoc Reader
5/21/19 6:26 p.m.

Hey guys.  I waved the white flag and took the car into my mechanic.  He said that my new turn signal assembly was at fault and I had fixed it already.  We have the car back and have been having fun with it.  Now we have to get going with rally cross prep.

I will post pictures when I start a build thread.

Thanks so much for all of your help, thanks Dan for the books.  They are going to come in handy as the car needs a ton of work. I I also got so mad at my lack of skill that I finally installed the boost gauge in my 06 mustang.  I cut into existing wires and soldered new ones in.  Something I had always been afraid to do.  Now I want to do more.

This "new" mustang is going to be a good learning experience, hopefully for my son as well.

Again, thanks for the encouragement.  

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