What's new
CK5
Register an account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members.

Dead Gauges?

H

Hop-up

Guest
I need some help on the gauges in my '78 K5. Speedo, volt, oil pressure, etc. are not working. Im guessing that they're just not getting power? I haven't pulled them yet, but ill do it today. Is there a central power source for all of them? The fuse is good, too. Could it be that they're fried?
 
If all dead, unlikely the gauges are bad. Make sure the ground(s) are good, pay attention to the condition of the cluster connector and the printed circuit board where they meet.

Speedometer doesn't get power, so that's not your problem there.
 
could the speedo have something to do with the Cruise Control box not being hooked up?
 
'78 would use a transducer, so yes. Speedo cable comes into the transducer, and comes out to feed the speedometer, also somehow providing the signal or whatever for cruise. Never dealt with that system, but cruise was part of the speedometer setup in all years of these trucks until 1990.
 
Ok, that makes it a bit clearer. There is a brown wire on the CC box thats not connected anywhere. The P.O. disconnected the CC set up becuase of the carb he put on there, i guess. Also took the deceleration valve off. Ill check my diagrams again, but maybe that brown wire needs power to connect the two speedo cables? Would there be a way to convert it to a single cable and go ahead and remove the CC box? since im not using it
 
I believe any of the trucks that didn't have cruise were either a one piece or two piece cable, just joined directly together. I can't recall if GM did a two piece cable and no cruise with the trucks or not, but I know they did on the cars.

To my knowledge the transducer is a physical connection of the cables through some gearing, so the brown wire is likely nothing other than a speed signal, and shouldn't affect operation of the speedometer if everything else is alright.

Someone will have to help you on what year cables will interchange. Somewhere prior to '81 the speedometer connection at the cluster/speedometer changed, so the cable end may be different depending on year.
 
My '78 k10 cable is one piece and i took it from an '87 Suburban parts truck that i had. It goes strait from the guage to the t-case. Not sure if that helps.
 
My '78 k10 cable is one piece and i took it from an '87 Suburban parts truck that i had. It goes strait from the guage to the t-case. Not sure if that helps.

Did the guages ever work?
 
They haven't worked since ive had the truck, so i don't know how long it's been. Im working on it now, the gas gauge is the one im really worried about, its top priority.
 
LMC lists a single (long) speedo cable for non-cruise control vehicles and two shorter ones for cruise control types for my 76.
 
Oops. Since the rest of my CC is toast, we're converting it with the longer cable. It's not electronic, just a twist cable.
 
Pretty common to just go to your local parts store and tell them you need a cable for a unit without cruise. The transducer reads the speed of the cable and modulates the vacuum for the module on the engine. There is nothing electronic about the system, and it is not really as accurate as newer systems.

Pull the cable out of the transfer case and run a drill on the cable to see if it moves the speedo. If not, check the cable end at the transducer for movement. If it moves at the transducer, the transducer is bad. If the speedo moves with the cable out of the transfer case, the gear in the transfer case is bad, or rounded out and not turning the cable. Edit, you need to see some movement of the speedo before you can rule out that it is bad.
 
yeah, make sure you check your wiring for that gas gauge. I have found that it is usually a wiring issue, and with that usually the ground. For the other gauges (volt, temp, pres) I have seen several vehicles with all those dead. No, they did not all short out at one time. Its just that these vehicles are getting old and previous owners didn't change them out as they no longer indicated everything. In other words it was a voltmeter that went bad 20 years ago, temp burned out 5 years ago, and oil pressure stopped working yesterday kind of situation.
 
Cool thanks.

i got the speedo working, just got a 1 piece. Pulled the engine compt. side of the fuse box, and all the connectors were highly dirty/corroded so i cleaned em off. We'll see if i can get the rest of the gauges working!
 
You must log in or register to reply here.

Latest Posts

Top Bottom