3rd brake works, mains do not?

[MickeySpiers]

On my newly acquired '97 Limited, the neon tube brake light works, but the two main taillights do not. The running lights work, the bulbs themselves are fine (handy having another Explorer to swap parts to/from) and when I put the voltmeter to the brake light socket, I have a constant 4 volts from the brake circuit to both the ground in the light socket (on both sides) and to the chassis, whether the brakes are on or not. Dunno why theres 4 volts there when the pedals not depressed, but it doesn't jump when the pedal is pressed, so I'm guessing this isn't right. The truck has a frame mounted tow hitch, but no electrical connector that I can see so I can't test there. I didn't bother to test the brake switch on the pedal, as the neon tube works. Any pointers on where I need to tear apart the rear panels to start troubleshooting?

 

[budwich]

you wouldn't happen to have the LOM option on the vehicle?

 

[MickeySpiers]

Maybe. What's an LOM? I chased my tail for a day trying to figure out why the parking lights were staying on for an extended period of time before I broke down & read the owners manual, learning that the slider bar on the rear view mirror actually controlled my running lights...

 

[MickeySpiers]

Ah, LOM - Lamp Out Module. If that's the fancy digital readout thingy under the climate control system, then yes, it does, but it's only currently complaining about the "tail lights" which happened when I unplugged the bulbs in the rear to test. So, it sees that. I've replaced the multi function switch to get my blinkers and hazzards working again, and had hoped that may cure the lower brake lights too, but it didn't.

 

[budwich]

you got it toyota... its your LOM module... fubarred. they are fixable sometimes, there are threads on it. At the module, check for voltage in (with brake on) on LG and out on R/W.

 

[MickeySpiers]

I'm now reading up tons on the LOMs, and guessing mine is the source of several problems this thing has. When I test drove it last week, the drivers headlamp was out, blinkers only half worked, no hazzards, no lower brakelights. The next day when I loaded it on the trailer to bring it home (front axle shot too) the headlights didn't work at all, and I had no foglights anymore either. I replaced the multifunction job to fix the blinkers/hazzards, hopefully the LOM will cure my remaining lighting issues - then I can start the fun of diagnosing my front end grind... Thanks!!

 

[budwich]

well... you might be chasing more than one problem. I don't think blinkers go thru the LOM... sounds more like an MFS switch problem. However, the "no headlamps" or "only one headlight" is a common problem since the amount of "juice" being feed is significant. Brake lights is usually but do travel thru the module as brake lights might be "important". Good luck.

 

[MickeySpiers]

More than one problem indeed... The new MFS I picked up from NAPA yesterday cured the blinkers and hazards, but did nothing for the low beam issue. The LOM drop of solder routine this evening cured my no lower brake lights (thank you Budwich) and magically the auto lock feature when you put the truck in drive started working again. Still no lowbeams tho... So, some more searching, and I see somebody trying to jump the red/yel to red/blk wires at the MFS to rule it out. So I tried that, and voila, fogs & passenger low beam come on. Still no drivers side. On the outside chance it might just be the bulb, I removed it, sure enough the filament is busted. New bulb, back in business. Guess I'm off to NAPA tomorrow for another MFS, hope this one fixes it!!

 

[MickeySpiers]

With the "new" MFS from NAPA, I know have both low beam & high beam output, but the passengers side low beam (and therefor driving lights) are out again. I'll toy with the lamp out module again, but on the assumption it's shot beyond a solder fix, anybody know the pins for me to jump at the LOM connector to ensure the problem is indeed that module?

 

[budwich]

DB/LG in DG / O out.

 

[MickeySpiers]

Thank you. Right headlamp & fogs work when jumped. Off to Courtesy Ford I go for a new module...