1989 RWD 4.0L MJ/ Headlight Dimmer Location

[Dal3]

I lost the low beams this evening.  Dimmer switch presently toggles between High Beams and OFF.  I looked at a replacement at O'reilly's.  Found  1 similar in left kick panel, 3 on RF fender liner.  I

pulled each of these and  the switch functioned exactly the same regardless of which.  Internet indicates fender liner relays related to  engine controls, but where is the dimmer relay located, PLEASE.

Thanks.

Dale

[Eagle]

This is actually shown as an '88 Manual, but it should help with closely related years as well. As with my other posts, please open it and save it to your computer...

 

https://comancheclub.com/applications/core/interface/file/attachment.php?id=14915 8.04 MB · 31 downloads

Edited April 14 by Pete M

[Dal3]

New question:  Is there a dimmer relay?

I thought dimming to be relay-controlled, because the dimmer switch appears to be of single throw, momentary contact type, but have been unable to find a dimmer relay in the manual.
 
Page 3 in the "Electrical Troubleshooting Manual" Under "How to Use This Manual,", "Connector End Views," states, "The location of the connector in the vehicle is included with the connector number."

In the schematic,on page 66, "Headlamps and Fog lamps," I found a dimmer switch with connector number, but no dimmer relay or connector number.

In "Component End view," Page 75 I Found dimmer switch connector and location, but no dimmer relay connector number or location.

Using the Acrobat search feature provided, I didn't get a result searching "dimmer," though it does appear in the document on pages 66 and 75 for the dimmer switch.

So, Is there a dimmer relay in the 1989 Comanche and if yes, where is it located in the vehicle or in the 1988 "Electrical Troubleshooting Manual.

Thanks.
Dale

[Ωhm]

5 minutes ago, Dal3 said:

New question:  Is there a dimmer relay?

No

Newer question: Why is it call a dimmer switch (C177)?

88 Electrical Manual is confusing. Its the Turn Signal Lever that controls LOW or HIGH beam circuit.

[JustEmptyEveryPocket]

The the turn signal lever actuates a rod that follows the steering column down to a switch. This switch controls high beam operation.

[Eagle]

4 hours ago, Ωhm said:

 

Newer question: Why is it call a dimmer switch (C177)?

88 Electrical Manual is confusing. Its the Turn Signal Lever that controls LOW or HIGH beam circuit.

 

It's called a "dimmer" switch because the switch that controls the headlight high or low beams has been called a "dimmer" switch for at least 75 years. It would be more confusing to change the terminology now.

 

The actual switch isn't just a turn signal switch, it's now a multi-function switch. It controls both the turn signals and the high/low beams. In newer vehicles, the same switch also controls the hazard flashers.

[Jeep Driver]

Your problem is not likely a relay if there were a relay. 

 

Check the plug near the air box. 

 

Or your multi switch has gone south. 

 

 

 

Pull the connector.....long connector.......off the column, use a test light to find the brights/low circuit, easy to find by toggling the switch, if you have power at the column- either the headlight switch itself is bad or the plug at the air box has fouled. 

[Pete M]

when I bought my first MJ the hi-beams didn't work.  turned out that rod had simply fallen out of place and wasn't pushing the switch at the base of the column.  Only took me YEARS to discover that tidbit of knowledge. 

[Warren Mohler]

dimmer switch is located lower left side of column and as others have stated is rod operated very awkward to get to a magnetic socket is recommended for removing and replacing screws be sure to not over tighten if replacing switch but I doubt this is your problem many times I have seen both headlamps burn out at the same time so check this first if lamps are ok continue on checking for power and ground do this at the lamp plug I have been working on these jeeps and many others for over thirty years  have never seen this dimmer switch go bad  you stated you still have high beams so ground should be good check all wire harness from  lamps rearward and all associated connecters for corrosion as far as I con remember there is no relay

Edited April 30, 2019 by Warren Mohler
a little more info to offer

[Dal3]

Thanks to everyone.  I first read replies this afternoon and got to inspect the truck about 6pm.  I've now read everything posted previous to this.  Yes, I see that this system is different than I'd envisioned it and that the switch and connector are accessible without additional disassembly.  I pulled the connector and checked components with testers and experiments. I also pulled one headlamp and the low beam filament was good. Low beams didn't come on even when powered by an auxiliary source from the connector (powered from the same source, the high beams did come on.)

 

I will copy pages 66 and 75 from the 1988 manual for careful study before proceeding.  From the dimmer switch connector at the switch, 5 wires (2 gr, 2 wh ,1br) appear to go left and back a little, then to enter a plastic loom and go forward.  The harness comes out low on the firewall through a rectangular block.  I can't tell whether or not this is a connector.  If it is a connector I'd like to get it apart and clean it.  Otherwise, it appears the headlight wiring comes out of the loom near the left front headlight and I'll test it there.  If the problem appears to be back in the loom, I expect I'll just bypass the original wire to back near the switch.

 

So, could anyone tell me if that large block under the clutch master cylinder is a connector and hint at getting it apart if it is.  I pulled on it some, but couldn't see it well in the available light.

 

Question for Jeep Driver: You said, "Check the plug near the air box."   I'm not sure I understand your terminology?  Is "plug" a connector and

"air box" interior heater ducting?  I've looked under the dash and hood and can't identify.

Thanks

Dale

[Jeep Driver]

44 minutes ago, Dal3 said:

Thanks to everyone.  I first read replies this afternoon and got to inspect the truck about 6pm.  I've now read everything posted previous to this.  Yes, I see that this system is different than I'd envisioned it and that the switch and connector are accessible without additional disassembly.  I pulled the connector and checked components with testers and experiments. I also pulled one headlamp and the low beam filament was good. Low beams didn't come on even when powered by an auxiliary source from the connector (powered from the same source, the high beams did come on.)

 

I will copy pages 66 and 75 from the 1988 manual for careful study before proceeding.  From the dimmer switch connector at the switch, 5 wires (2 gr, 2 wh ,1br) appear to go left and back a little, then to enter a plastic loom and go forward.  The harness comes out low on the firewall through a rectangular block.  I can't tell whether or not this is a connector.  If it is a connector I'd like to get it apart and clean it.  Otherwise, it appears the headlight wiring comes out of the loom near the left front headlight and I'll test it there.  If the problem appears to be back in the loom, I expect I'll just bypass the original wire to back near the switch.

 

So, could anyone tell me if that large block under the clutch master cylinder is a connector and hint at getting it apart if it is.  I pulled on it some, but couldn't see it well in the available light.

 

Question for Jeep Driver: You said, "Check the plug near the air box."   I'm not sure I understand your terminology?  Is "plug" a connector and

"air box" interior heater ducting?  I've looked under the dash and hood and can't identify.

Thanks

Dale

Right behind the headlight, between the air cleaner box and the headlight. 

[Jeep Driver]

7 hours ago, Pete M said:

when I bought my first MJ the hi-beams didn't work.  turned out that rod had simply fallen out of place and wasn't pushing the switch at the base of the column.  Only took me YEARS to discover that tidbit of knowledge. 

Good call, didn't even think about the rod/switch.

[Dal3]

Resolution, 

I'm just getting the last message.  At my last post, I'd already decided to move next into the area in front of the air cleaner housing box described by "Jeep Driver" for close inspection.  This required more disassembly than I have done before to get to the headlight wiring, but wasn't too bad.  First, I disconnected the headlight wiring from the harness.  The connectors were so badly corroded I wanted to acid clean and grease the connection, but all I had on hand was "Deoxit", so treated with that.  I had noticed insulation cracking in the leads from the harness, then saw there was a broken green wire which proved to be the source of the problem.  My rural house and workshop burned last year so, as with the corrosion problem, I was ill equipped to properly repair but stripped the wires back and twisted them tightly, which should hold for a while.

Thanks for all the helpful suggestions.

Dale

[Jeep Driver]

3 hours ago, Dal3 said:

Resolution, 

I'm just getting the last message.  At my last post, I'd already decided to move next into the area in front of the air cleaner housing box described by "Jeep Driver" for close inspection.  This required more disassembly than I have done before to get to the headlight wiring, but wasn't too bad.  First, I disconnected the headlight wiring from the harness.  The connectors were so badly corroded I wanted to acid clean and grease the connection, but all I had on hand was "Deoxit", so treated with that.  I had noticed insulation cracking in the leads from the harness, then saw there was a broken green wire which proved to be the source of the problem.  My rural house and workshop burned last year so, as with the corrosion problem, I was ill equipped to properly repair but stripped the wires back and twisted them tightly, which should hold for a while.

Thanks for all the helpful suggestions.

Dale

 Most of us have installed new headlight harnesses.......when you get back up and running with your shop.........look up "harness upgrade' and  you'll find info ad nauseum.