2nd Gen Non-Engine/Transmission flasher problem, electrical wizards welcome

[QWaller]

My 98 just started with a flasher problem. Flashers (turn signal) work normally, then, apply brakes and signal freezes on (lit) no longer flashing,signaling. Will start back if brake pedal released. Hazards work normally (braking or not). Bulbs are all working normally otherwise in all trials of signals etc. Replaced the flasher module with Advance Auto Tridon unit. No difference at all. Any suggestions? Thanks

 

[SSolderitch]

You may have a shorted bulb, bad relay or MFS. Try the easiest first - realy swap with another, take one rear bulb out at a time.

 

[rrl989]

The 98 uses an electronic combination flasher. Turn signaling uses 'sense' voltages directly compared to the supplied battery voltages. An IC controls the flash rate and compensates for higher current as required, I'm guessing up to a certain point, I wonder if you may be introducing a short somewhere with the brake depressed and effecting either the sense or battery input VDC? Do you have trailer wiring tied in to your system?

 

[Missouri Mule]

Are you sure your backlights are flashing when your foot is on the brake?

In my experience with vehilcles while braking the brake lights over ride the flasher signal.

Your light indicators on the dash seem to be doing the job just fine. Of course I haven't used my flashers that often and not for many years on the Mule.



Just noticed you were talking about turn signals. Sorry! I take it you replaced the multi-function switch(flasher module)?

 

[QWaller]

I do have trailer wiring hooked in and I too think there is some source of short or grounding problem somewhere. The problem disappeared today and was acting normal, BUT I am worried that it could happen again at any time, possibly increasing my chance an accident.

 

[fest3er]

Looking at the wiring diagrams, I can think of only three things (in order of decreasing likelihood based on my recollection of complaints in these here fora):

• You've a short in your steering column wiring harness, possibly shorting both turn signal leads together enough to make the central timer module (CTM) think you had the hazards on, in which case it would stop flashing when the brake is applied.
• The turn signal/hazard switch on the steering column is flaky and somehow cause the timing control unit to think the hazards were on when you only had a turn signal on off on off on off... , again making the CTM stop flashing as above.
• The CTM is losing its mind.

If it happens again, reach behind the knee bolster and jiggle the harness. If you're very lucky, the problem'll be somewhere near there.

 

[DieselDoghouse]

Check what Fest3er said above - also disconnect the harness connector to the trailer plug in case you have a corrosion/short problem within the weather-exposed trailer jack (very common).

 

[QWaller]

Thanks for the help guys. I will try these items. Hope to get them to start acting normally.