Head light issues

[Andrew Hare]

I have the LMC after market harness in my 1988 Jimmy went to install the switch for my plow lights in my truck now I have no high beam lights on my truck but I have both high and low beam lights on my plow lights what are anyone’s thoughts?

 

[MEMO43]

check the grounds
I have similar issues an it was at the headlight connection the pigtails were loose at the connection

 

[Andrew Hare]

Well the issue I’m having is the High Beam indicator only comes on when my head lights are set to the truck lights. When they are set to my plow lights the high beam indicator doesn’t work. That’s what I’m trying to figure out cause it’s not making any sense to me at this point.

 

[dyeager535]

Well the issue I’m having is the High Beam indicator only comes on when my head lights are set to the truck lights. When they are set to my plow lights the high beam indicator doesn’t work. That’s what I’m trying to figure out cause it’s not making any sense to me at this point.

Pdf page 251 if this link works http://www.mediafire.com/file/jcnww...t_Truck_Wiring_Manual_Complete_11x17.pdf/file

Not much info, but pg 301 shows the cluster wiring and park of the high beam display. I'm guessing it's fed power off the high beam wire somehow, since that bulb shares a ground with all the other gauge lights, and the positive side of that circuit doesn't come from the headlight switch.

If the above link doesn't work, you can find the link to the '88 electrical manual here http://67-72chevytrucks.com/vboard/showpost.php?p=5621043&postcount=1

 

[Wes Harden]

Let me understand, you are using the headlight switch for both the truck and plow lights?
Or you you have the truck wiring to the only the plow lights?
Or do you have 2 separate switches for plow and truck lights?

 

[Andrew Hare]

I have one switch that can switch between the truck and plow lights. It’s a 6 pin switch. The low beam and high beam wires get cut and the switch goes in place between the dimmer switch and the truck’s headlight harness. The low beam & high beam wires come off of the dimmer switch and go into this switch and depending on what direction the switch is thrown you have either Truck lights or plow lights not both at the same time. My GMT400 has the same set up.

 

[Wes Harden]

So using the dip switch on the column should indicate hi beams no matter which set of lights is selected.

Hmm weird. Gonna study this some.

 

[Wes Harden]

So the way I understand this, the high beam power also powers the high beam indicator lamp. The diagrams I have seen show the power splice at the switch, but they have all been non GM drawings.
My guess is that you spliced your plow light switch in before the indicator splice. This would explain why indicator works in truck mode but not plow mode.


FYI if you didn't already know, an 88 truck wiring is different than an 88 Blazer/Jimmy/suburban

 

[Andrew Hare]

My guess was the indicator splice was up behind the gauge cluster so I spliced power in from down near where the headlight harness runs thru the firewall down by the fuse panel. But apparently I was wrong. If anyone knows where the indicator splice is please let me know.