No Brake lites, Hazards or Turn Signals

[floridacruiser]

I tow a 1999 Dodge full size van behind my Class A motorhome. I put diodes in the taillights for towing. Here's the problem!! I have towed this vehicle successfully for the past 6 years with no problems. On my last trip while unhooked from the MH and cruising around town, the brake lights, hazards and turn signals quit working.

I have replaced the multi-function switch (on the steering column) and fuse box (end of drivers side dash) in the van per a local garage which said they were bad. Still no lights!!!  Could there be a problem with the diodes and they burnt something else out in the van? I'm just fishing right now as I am up against the wall not knowing what to do next.

Any one run into this problem???  All help would be appreciated!!!

Thanks............Floridacruiser

 

[Karl]

Could there be a problem with the diodes and they burnt something else out in the van?

Short answer: Yes.

When a diode fails, it will usually short out rather than open up like a lightbulb, and take out fuses, etc. Can't say for certain about your Dodge, but some vehicles use a fusible link to power those lights. It's part of the wire itself, and must be replaced. Also check for a bad circuit breaker or fuse. The c.b.'s for the lights are normally self-resetting but may not be doing so. A bad ground is also a possibility, but not likely. If it were a ground, you may expect any one of those lights to malfunction but not all of them at the same time. Still worth checking.

 

[floridacruiser]

Thanks for the reply. Checked circuit breaker and fuse before purchasing other parts. The garage also checked them and said they were OK. Got access to a wiring diagram next week and will check for a fusible link.

Thanks again.............Floridacruiser

 

[John From Detroit]

I can give you the troubleshooting procedure, however yes, diodes can indeed fail open, (or shorted) I have seen them go both ways, though not in this service

I have seen brand new diodes be open

Now, one of the interesting things is that ALL the lights went out at the same time.

This suggests to me that an in-line connector may have either 1: Seperated or 2:Corrouded

The procedure to follow is this,,, Find a location where there is power to the lights... I would suggest the load side of teh brake light switch as it's easier to get to.. Make sure there is indeed power there (Hook up a test light, press pedal and make sure light lights)

now find a place close to the non-working lamps  The test light should notwork here,,, If it does, repalce the bulb and/or check the socket for corrousion and the ground connection for bad wires.

Now move from one of those points toward the other,,, Every time you come to a splice or connector check both sides of the splice or connector

TO make a test light.... You will need    a 12 volt bulb, dome light lamps work well here,  A length of wire, say about 3 feed, strip the ends and attech one end to one end of the dome lamp bulb (if this is the tubler bulb with connections on both ends it works best to wrap the wire around the bail like wire end on the bulb) tape off with tape that can take heat.

Attach the other end to a small "Battery" type clamp  (this is the ground wire, clamp on any good ground bolt)

Take about a 10-20 foot length of wire and strip one end, attach this end to the other end of the bulb in the smae manner

The other end, shove a straight pin right through the middle of the wire,,, This is your test probe, you shove it right through the insulation of the wire to be checked.

After testing you might wish to brush the test points with liquid electrical tape to re-seal the holes so the wires don't corrode away

 

[floridacruiser]

John: Thanks for the reply. I have a third brake light. Apparently the third brake light is on it's own circuit. I assume the brake switch is fine and has juice going through it. NOW...I can push the Hazard Switch on the column down and lock it and I have brake lights and the third brake light. If you leave the Hazard Switch engaged the brake lights work fine but I still have no turn signals or hazards.

STRANGE!!!!!

 

[John From Detroit]

John: Thanks for the reply. I have a third brake light. Apparently the third brake light is on it's own circuit. I assume the brake switch is fine and has juice going through it. NOW...I can push the Hazard Switch on the column down and lock it and I have brake lights and the third brake light. If you leave the Hazard Switch engaged the brake lights work fine but I still have no turn signals or hazards.

STRANGE!!!!!

I have one vehicle (I think it's the motor home w/o checking) where the hazard flasher switch works oppisite of how I think it should work... That could be the issue.  with the hazard switch in the ON position you should have flashing lights on all 4 corners, the 3rd eye stop light will also work if your stop lights are also turn signals (else it won't)

So if everything is workign normally with the hazard switch in what you think of as "ON" that coudl be the issue

 

[floridacruiser]

John: Everthing is not working. I still don't have turnsignals or hazards with the hazard switch on!!!! It seems with the hazard switch on...it is providing a ground to the brake lights.........thus the brake lights work if you engage the hazard switch.

Getting a wiring diagram shortly and will have to diagnose the problem. Thanks for your input!!!

 

[John From Detroit]

A wireing diagram will help... However be aware that wireing diragrams often do not show in-line connectors unless they connector does something like combine 2 lines into one (or split a line in two) so it might miss a corrorded connection in a door or rocker panel or fender compartment.  The only way to be sure is trace it out

 

[floridacruiser]

John: Got a wiring diagram and started tracing wires. Guess what??????? In less than 5 minutes we found that the main junction block  (not the fuse panel) on the inside of the van down by the bottom of the steering column had corrosion on a couple of pins that was causing no 12 volt to the turnsignal flasher in the fuse panel. Cleaned it up and put it back together and everything works fine.

Learned a valuable expensive lesson.........Get a wiring diagram from Mitchell Wiring Diagrams @  http://www.eautorepair.net/  for only $7.99 for one weeks use. Works like a charm!!!!

 

[John From Detroit]

Learned a valuable expensive lesson.........Get a wiring diagram from Mitchell Wiring Diagrams @  http://www.eautorepair.net/  for only $7.99 for one weeks use. Works like a charm!!!!

Thanks for the link... Yes, knowing what wire goes where is a very big help on many occasions.. Which reminds me of something

 

[Ron]

Glad to hear you found the problem and was able to fix it.