Burning up switches...

[joester1908]

So I have a 1990 Comanche. My heater only worked on 1, (2, 3, and 4 were the same as 1). I replaced the resistor. I also checked the heater switch. The plug was melted, so i replaced the plug and switch. I reassembled everything and almost immediately the dash lights flickered and I popped the fuse. I installed a new fuse, and they did not work, but the fuse didn't pop for a minute or 2. I then pulled the headlight switch. The plug was melted and the switch was heavily corroded. (You can see images on my build thread, I can't attach photos from the school computer). I spliced in a new plug and installed a new headlight switch. It worked for a few days, but yesterday i flicked on the lights, they flickered and turned off. 

 

Is there any connection between the heater and the headlight switch? Or is it just coincidece that they both went out at the same time.....if there was something like a common ground could that be giving me issues?

 

I inspected all of the wiring in the dash and behind the heater, and I didn't find any shorts or broken wires. But even if there was a short that shouldn't melt a headlight switch, right? I am planning on doing a relay swap soon enough, but in the mean time I only have headlights, no dash lights or marker lights. I have yet to pull the switch I just installed, but thats the next step.

 

Any input is appreciated. Thanks guys....

[ftpiercecracker1]

So I have a 1990 Comanche. My heater only worked on 1, (2, 3, and 4 were the same as 1).

 

Are you saying the blower only worked on the slowest setting?

 

I replaced the resistor.

 

What resistor? The one attached to the black HVAC box behind the glove box?

 

I also checked the heater switch. The plug was melted, so i replaced the plug and switch.

 

So, you replaced the blower motor switch and plug. The switch that controls the speed of the blower?

 

I reassembled everything and almost immediately the dash lights flickered and I popped the fuse. I installed a new fuse, and they did not work, but the fuse didn't pop for a minute or 2.

 

But it did pop eventually even though the lights never came on?

 

I then pulled the headlight switch. The plug was melted and the switch was heavily corroded. (You can see images on my build thread, I can't attach photos from the school computer). I spliced in a new plug and installed a new headlight switch. It worked for a few days, but yesterday i flicked on the lights, they flickered and turned off. 

 

Do you have your Hi and Low beams wired together?

 

Is there any connection between the heater and the headlight switch? Or is it just coincidece that they both went out at the same time.....if there was something like a common ground could that be giving me issues?

 

I inspected all of the wiring in the dash and behind the heater, and I didn't find any shorts or broken wires. But even if there was a short that shouldn't melt a headlight switch, right? I am planning on doing a relay swap soon enough, but in the mean time I only have headlights, no dash lights or marker lights. I have yet to pull the switch I just installed, but thats the next step.

 

If there is a bad connection at the HL switch it can cause enough resistance to melt the plug, the same goes if there is to much draw. Hence why i asked about the Hi and Low beams.

 

Any input is appreciated. Thanks guys....

 

 

 

The grounding system throughout the whole truck is severely inadequate. If you havent already I would strongly recommend upgrading/refreshing all current grounding points and maybe even add a few.

 

Also the bulkhead connector that goes through the fire wall can produce significant resistance if not thoroughly cleaned.

[joester1908]

 

So I have a 1990 Comanche. My heater only worked on 1, (2, 3, and 4 were the same as 1).

 

     Are you saying the blower only worked on the slowest setting?

 

          Yes

 

I replaced the resistor.

 

     What resistor? The one attached to the black HVAC box behind the glove box?

 

          It was under the passenger side dash, yes. under the blower motor off to the left side.

 

also checked the heater switch. The plug was melted, so i replaced the plug and switch.

 

     So, you replaced the blower motor switch and plug. The switch that controls the speed of the blower?

 

          Correct

 

I reassembled everything and almost immediately the dash lights flickered and I popped the fuse. I installed a new fuse, and they did not work, but the fuse didn't pop for a minute or 2.

 

     But it did pop eventually even though the lights never came on?

 

          Yes. The lights never came on, and the fuse eventually popped.

 

I then pulled the headlight switch. The plug was melted and the switch was heavily corroded. (You can see images on my build thread, I can't attach photos from the school computer). I spliced in a new plug and installed a new headlight switch. It worked for a few days, but yesterday i flicked on the lights, they flickered and turned off. 

 

     Do you have your Hi and Low beams wired together?

 

          I don't think so. I just hooked the colors up and spliced them together, just like the plug was...

 

Is there any connection between the heater and the headlight switch? Or is it just coincidece that they both went out at the same time.....if there was something like a common ground could that be giving me issues?

 

I inspected all of the wiring in the dash and behind the heater, and I didn't find any shorts or broken wires. But even if there was a short that shouldn't melt a headlight switch, right? I am planning on doing a relay swap soon enough, but in the mean time I only have headlights, no dash lights or marker lights. I have yet to pull the switch I just installed, but thats the next step.

 

     If there is a bad connection at the HL switch it can cause enough resistance to melt the plug, the same goes if there is to much draw. Hence why i asked about        the Hi and Low beams.

 

          With the headlights on, it's only low beams or only high beams, so I don't think they're wired together. What would cause resistance at the switch? The plug was in good shape and the switch itself is brand new.

 

Any input is appreciated. Thanks guys....

 

 

 

The grounding system throughout the whole truck is severely inadequate. If you havent already I would strongly recommend upgrading/refreshing all current grounding points and maybe even add a few.

 

Also the bulkhead connector that goes through the fire wall can produce significant resistance if not thoroughly cleaned.

 

[cruiser54]

Click on the link below and do Tips 1 and 3. 

[joester1908]

Click on the link below and do Tips 1 and 3. 

I basictally have done that. I don't have the C101, but the plug on the headlight switch and blower switch is new, and both switches themselves are new. As for ground refreshing, I have done that with the dipstick and the braded cable. My question is is there a common ground for both the blower switch and the headlight switch? There is a ground lug on the back side of the headlight switch that does somewhere under the dash, but i put my multi meter on it and it was giving me a good ground.

[HOrnbrod]

Which headlamps are you running? Halogens or the stock sealed beams?

[joester1908]

Which headlamps are you running? Halogens or the stock sealed beams?

I have an XJ Wagoneer header panel, the one with 4 different lights. But they're just stock halogens

[cruiser54]

Wiper grounds on the driver's side inner fender. 

 

Ever read my Tip 18?

[joester1908]

Wiper grounds on the driver's side inner fender. 

 

Ever read my Tip 18?

I will check that out. Thank you

[ftpiercecracker1]

My question is is there a common ground for both the blower switch and the headlight switch? There is a ground lug on the back side of the headlight switch that does somewhere under the dash, but i put my multi meter on it and it was giving me a good ground.

 

 

 

I don't know about the first part, but the connector on the back of the HL switch utilizes the interior wiring harness ground. Under the knee panel on the left hand side of the steering column.

 

The HL wiring harness itself could be the source of your problem or more likely the HL harness connector under the hood. The connector is located on the drivers side, right underneath the factory air filter location. Look for a big black connector.

[cruiser54]

 

My question is is there a common ground for both the blower switch and the headlight switch? There is a ground lug on the back side of the headlight switch that does somewhere under the dash, but i put my multi meter on it and it was giving me a good ground.

 

 

 

I don't know about the first part, but the connector on the back of the HL switch utilizes the interior wiring harness ground. Under the knee panel on the left hand side of the steering column.

 

The HL wiring harness itself could be the source of your problem or more likely the HL harness connector under the hood. The connector is located on the drivers side, right underneath the factory air filter location. Look for a big black connector.

 

Correct. See Tips 3 and 18 for photos.

[joester1908]

 

My question is is there a common ground for both the blower switch and the headlight switch? There is a ground lug on the back side of the headlight switch that does somewhere under the dash, but i put my multi meter on it and it was giving me a good ground.

 

 

 

I don't know about the first part, but the connector on the back of the HL switch utilizes the interior wiring harness ground. Under the knee panel on the left hand side of the steering column.

 

The HL wiring harness itself could be the source of your problem or more likely the HL harness connector under the hood. The connector is located on the drivers side, right underneath the factory air filter location. Look for a big black connector.

 

You may be right. I know of the ground you are talking about, that will be the first thing I check. As for that harness, i remember it being a little green in there when i did my Wagoneer swap. 

[joester1908]

 

 

My question is is there a common ground for both the blower switch and the headlight switch? There is a ground lug on the back side of the headlight switch that does somewhere under the dash, but i put my multi meter on it and it was giving me a good ground.

 

 

 

I don't know about the first part, but the connector on the back of the HL switch utilizes the interior wiring harness ground. Under the knee panel on the left hand side of the steering column.

 

The HL wiring harness itself could be the source of your problem or more likely the HL harness connector under the hood. The connector is located on the drivers side, right underneath the factory air filter location. Look for a big black connector.

 

Correct. See Tips 3 and 18 for photos.

 

I went through the tips again and read number 18. Thank you for posting that, huge help. I'll let you guys know how it turns out...Gonna start tomorrow after school

[joester1908]

Thank you guys for the help. I believe it was a grounding issue. I made a jumper to a better ground (which, someone kind of already did, but did a very poor job. Also, the grounding cable was loose...) and I also cleaned the headlight harness plug, which was green. Everything is working now. Thanks again!

[cruiser54]

Thank you guys for the help. I believe it was a grounding issue. I made a jumper to a better ground (which, someone kind of already did, but did a very poor job. Also, the grounding cable was loose...) and I also cleaned the headlight harness plug, which was green. Everything is working now. Thanks again!

Woohoo. Way to stick with it. 

[joester1908]

 

Thank you guys for the help. I believe it was a grounding issue. I made a jumper to a better ground (which, someone kind of already did, but did a very poor job. Also, the grounding cable was loose...) and I also cleaned the headlight harness plug, which was green. Everything is working now. Thanks again!

Woohoo. Way to stick with it. 

 

thanks!