Comanchemodder Posted January 3, 2013 Share Posted January 3, 2013 Problem: Brake lights do not work.Need help diagnosing the problem so I can pass vehicle inspection. There may be a few electrical problems, but the critical issue at hand is the brake lights. Truck: 1987 2.5l, AX4 2WD. Symptoms:1) Running lights work. Therefore I assume the ground is good? 2) Turn signals work. They are s..l..o..w.. when the lights are on, normal speed when the lights are off. 3) Turn signal dash lights: When the running lights are on, both signal (little green arrows) are "on" even though the signal is not activated. When the running lights are turned off,the signal indicators function properly (blink as expected). 4) I am missing a few fuses (see pic) but all the shown fuses are in working order. The fuses shown is the way the truck came from PO; i have not touched them, only to verify they are not blown. 5) The brake light switch (see pic) reads 12 volts when the pedal is not depressed. It reads zero volts when pressing the peddle.Where do I go next? Link to comment Share on other sites More sharing options...
KYMJ Posted January 3, 2013 Share Posted January 3, 2013 New turn signal bulb sockets will cure the green dash indicator light problem. You say the brake light fuse is good? Does your fuse block show signs of corrosion from hyd fluid(clutch m/c)? The brake light fuse does not make good contact in my fuse block due to corrosion(still haven't fixed it yet) . I have to jiggle it now and then when I notice my brake light not working. Yes, I check often, don't want to get rearended. Check yours to see if its making good contact. Might be a possibility. Link to comment Share on other sites More sharing options...
Pete M Posted January 3, 2013 Share Posted January 3, 2013 to post pictures, you need to first click the image button above the text box. It's a little greenish square. then you can paste the address in the pop-up box and it'll show up in the thread. :thumbsup: Link to comment Share on other sites More sharing options...
vaquaro Posted January 3, 2013 Share Posted January 3, 2013 Brake light switch bushings worn ? Insert a narrow screwdriver between switch and booster push rod , if you get lights that's the problem . A narrow thin shim ( fold to a " c" shape) will fix it :thumbsup: Link to comment Share on other sites More sharing options...
KYMJ Posted January 3, 2013 Share Posted January 3, 2013 New turn signal bulb sockets will cure the green dash indicator light problem. You say the brake light fuse is good? Does your fuse block show signs of corrosion from hyd fluid(clutch m/c)? The brake light fuse does not make good contact in my fuse block due to corrosion(still haven't fixed it yet) . I have to jiggle it now and then when I notice my brake light not working. Yes, I check often, don't want to get rearended. Check yours to see if its making good contact. Might be a possibility. That was a quick answer by me @3am at work on crappy computer. Your fuse block looks pretty good. You going to have to get your test light out and trace wiring-power into fuse, power past fuse-power to switch, from switch, etc. check above(vaquaro's suggestion) sorry no easy answer on brake lights like the sockets for other problem. Link to comment Share on other sites More sharing options...
87MJTIM Posted January 3, 2013 Share Posted January 3, 2013 I had the same issues. Running light, turn signal and flashers all work, but no brake lights. Replaced the turn signal switch in the steering column. Napa: http://www.napaonline.com/Catalog/Result.aspx?Ntt=turn+signal+switch&Ntk=Keyword&Nty=1&N=599001+101987+50038+2038006 Link to comment Share on other sites More sharing options...
buffalob Posted January 3, 2013 Share Posted January 3, 2013 Brake light switch bushings worn ? Insert a narrow screwdriver between switch and booster push rod , if you get lights that's the problem . A narrow thin shim ( fold to a " c" shape) will fix it :thumbsup: If the fuse is good this is the first thing I would check.... That's what my problem was.... Link to comment Share on other sites More sharing options...
Comanchemodder Posted January 5, 2013 Author Share Posted January 5, 2013 The plot thickens... Next symptom: To verify, which bulb(s) are the brake lights? On each side there are three bulb sockets. For the brake lights, I assume it will be one or both of the bulbs which are not the back-up lights. Now, for the observation: Driver side: running lights will activate one filament on both bulbs. Turn signal activates the second filament on both bulbs. Passenger side: running lights activate one filament on both bulbs. Turn signal activates second filament on both bulbs. What the!? Something can't be right, no available filaments for the brake light? Is it a shared circuit? Link to comment Share on other sites More sharing options...
87MJTIM Posted January 5, 2013 Share Posted January 5, 2013 See this thread: http://comancheclub.com/topic/12083-electrical-manual/ Download the pdf. Link to comment Share on other sites More sharing options...
Pete M Posted January 5, 2013 Share Posted January 5, 2013 the brake lights and turn signals are the same filaments. :thumbsup: Link to comment Share on other sites More sharing options...
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