any one know what this plug is for

[F-ingrob]

its on the same harness under the dash by the ash tray
my friend just did a cab swap and cant remember where it went (he didnt mark it)
its on a 85 K5 Diesel hopefully the pics came through

 

[dyeager535]

Wait light? Low coolant (or was it water in fuel?) light?

Wiring diagram for an '85 is probably found in the link in my sig, should be pretty easy to find.

 

[JDNobodi]

Well that is strange, a weather pack inside the cab. Either the previous owner installed the plug or he moved the wires with the plug inside the cab.
Most of the wires goes though the bulkhead connector on the drivers side. However added circuits for certain things pass though the firewall. (th400 kick down circuit comes to mind. It is a add-on circuit.)

I'm going for a guess without looking at any schematics.
The four wheel drive indicator light switch on the transfer-case.

 

[JDNobodi]

I have ruled out water in fuel sensor. That plug has 3 wires.

 

[JDNobodi]

Hmm, back up light connector use the two prong weather pack(for a manual transmission.) but the color code seems wrong. The wires should be green and lime green.

 

[JDNobodi]

Wait light? Low coolant (or was it water in fuel?) light?

Wiring diagram for an '85 is probably found in the link in my sig, should be pretty easy to find.

holy ****. I downloaded the pdf and try to enlarge the wire diagrams and it came out blurry. I couldn't read it.

 

[JDNobodi]

Well, I checked Rock Auto to see diagrams of their electrical connectors. Too bad they had the gas and diesel categories mixed up. I still feel that connector belongs out side the cab due to it being a weather pack and there is grime on it.
My best guess is the 4wheel drive indicator light switch on the transfer-case.
I let other people with more experience with that truck to lead you now.

 

[dyeager535]

Yeah, the t-case indicator light seems a good guess. Can't really tell from the pics the exact colors, but my 1990 R/V wiring diagram shows the 4WD indicator as gray & black or black & white, with RWAL and without RWAL, respectively.

 

[F-ingrob]

thanks for all the help guys i will let him know
i does look like the plug on my 208 so maybe its for his
he did tell me that the wires (black and white come from the same harness as the light in the pic but didnt tell me how long the lead was

 

[dyeager535]

That makes sense then. IIRC GM did run the 4WD light separate from the rest of the cluster wiring, probably to have one body wiring harness for all trucks 2 or 4WD, with that as an addition for the 4WD trucks only. I bet it saved them $.30 per truck!

 

[F-ingrob]

it was the T/case plug and the light for the shifter
thanks for all the input

 

[JDNobodi]

Wow, I wish I made money on my guesses.