No tail lights or cluster lights

[Trogdor]

I just replaced the cluster lights since they weren’t working before. I go to put everything back together and they still don’t work. Out of curiosity I checked all the markers, heads and tails. Only ones not working is the tail lights. The hazards and blinkers and brake lights work but the tail lights don’t illuminate when I turn on the headlights.

I got a circuit probe and it’s lighting up at the the switch on the red and orange. I really need some help here guys.

 

[Blue Ox]

Cluster lights maybe a dimmer issue? The potentiometer tends to have problems.

 

[Trogdor]

Thanks for the reply. I’ve been messing with it all day and I just noticed that the light in the heater module only comes on when the knob is turned all the way just before it clicks. Makes me think this might be the issue.

 

[Trogdor]

I just noticed that with the headlight switch turned off the interior lights stay on. Just ordered a new switch and will update when it comes in.

 

[Blue Ox]

Turned all the way counter-clockwise the interior lights are supposed to stay on. Turned clockwise past the detent it becomes a dimmer for the inst lights.

 

[Trogdor]

Yep, even turned clockwise all the way, interior lights were still on.

 

[idahovette]

Bad door switch??

 

[Trogdor]

I’m at a loss. I’ve traced wires and they look good. I installed the new switch and the underdash light now shuts off but the cluster lights don’t work still nor do the taillights. I also have some lighted under dash gauges and those lights won’t shut off. I know my way around an automobile but electrical has always stumped me.

 

[Cuba]

A huge contributer to interior lights staying on would be a shorted door switch, and it's grounded all the time. Or... the wire for that system somewhere is rubbed or melted through completing that circuit. Courtesy lights and lights under the dash are all the same system... the courtesy light.

The lack of dash & tail lights must be related, they come out of the same dimmer switch. Need to look at schematics, and verify things.

You say you traced wires? How did you check them? Test light? Meter? Meter would not be as accurate as a test light in this situation, because you want to load circuits to verify they're intact. Use an incandescent one.

 

[Blue Ox]

There may be several separate issues. The tail lights, are we sure the small filament in the bulbs is good? Could just be bad bulbs. The inst lights, there's a lot of places where that can go wrong. The connector at the hedlight switch, the connector at the cluster, the circuit board, the little bulb holders. IIRC the inst lights are on a gray wire, maybe you can chase that around and check for voltage.

Sorry if I'm telling you everything you already know, but I can't see it from here and I don't know how much you've already covered.

 

[Cuba]

Some vehicle info would help to see what schematics to look at too.

 

[Trogdor]

It’s and 84 Scottsdale.

If the brake lights work then would the taillights/markers still not work? I’ll have a few minutes to check a few more things before I leave for work. Maybe try some new bulbs.

This weekend I’ll trace and check wires more in depth this weekend. I wasn’t extremely thorough since it was 96 and humid.

 

[Blue Ox]

There are two filaments in the taillight bulbs. The larger, higher wattage one is the brakelight/directional, the smaller lower wattage is the taillight. It could also be the circuit, but I like to start with simple and cheap, like me.

 

[73c20jim]

It’s and 84 Scottsdale.

O look! It's the same as his signature.

 

[Blue Ox]

And we wonder why he's called Grumpy Jim.