A Question About Lights

[Super Warrantman]

I happened to notice recently on my M880 that the parking lamps are not on when the headlights are on. There's nothing wrong with them. They flash when I use the turn signals and they seem to be on when I have the light switch puled out to just the parking lamp setting, but I thought that they were supposed to remain on with the headlights. Starting with the 1969 model year all car makers were mandated by the govt to have the parking lamps stay on when the headlights were also on as a safety feature. Unless that didn't apply to trucks, shouldn't mine be lit too? It is, after all, a 1977 model.

I'm leery of digging into the wiring as things are working OK now, but I thought I would ask the question. The fellow I bought the truck from hinted that M880s were known to have electrical gremlins from time to time and he seems to be right as I've experienced the fluctuating gas gauge and temperature gauge on occasion.

 

[diesel583]

Mine are on with the headlights. Check your bulbs, it's possable both are bad. They use 1157A one side for parking light, the other for turn signal.

 

[Super Warrantman]

Thanks for the info. I'll check them out.

 

[N1265]

They should be on with the headlights. When you turn on the headlights and loose the front parking lights, do you also loose the tail lights ?

If not, then the problem should be in the front of the truck.

If so, then the problem could be the light switch itself .

also try to wiggle the BO lite switch lever and see it it makes any difference, it should be in "Service Drive "

 

[Super Warrantman]

OK I checked all lights and found that the only bad one was a 1157 bulb in the left rear. I replaced that one with a new one and it seems to be good now. Lighting test results are as follows:

1.) Headlamps - OK both low and hgh beam
2.) directional indicators - both left and right (front and back) are OK
3.) Emergency flashers (4-way) - OK
4.) Dash lights - OK
5.) Dome light - OK
6.) Stop lights (rear) - OK
7.) Back up Lamps - OK
8.) Tail lights - No Joy
9.) Parking lamps (front) - No Joy

I replaced the 20 amp fuse in the fuse box for the tail and park lamp circuit but it didn't make any difference. It still doesn't work.

The levers were missing from the military light control panel when I picked up the truck, but the seller told me that the B.O. lighting circuit was disconnected when the truck was refurbished. The park lamps and the tail lights were working when I picked up the truck.

It sounds as if the light switch (civilian) may be the culprit. Are there any other suggestions as to wiring weaknesses of the M880 that I should check?

 

[goodbrewing]

There is a wire on the plug of my headlight switch that runs the parking lights that was loose and had gotten hot. When it was modified the piece on the plug that holds the connector in was broken. I took the plug off the switch, cleaned all the connections and when I put the plug back I used a small screwdriver to push the connecters on. You may also want to follow the wires and make sure whoever re-modified it back did it right. If all is well there you may have a bad switch.

 

[N1265]

Check the Brown wire at the bulkhead connector ( both sides and both positions) If no power coming into the connector then check at the headlight switch itself,
( both in park and headlight "on" position )

Then if still no power, check to see if you have power coming into the light switch from the green wire. ( this wire comes from the fuse box for the parking lights) check these connections and let us know what you find out.


this can be done with a 12v test light.