Dash stops working when I turn on lights

[ullose272]

Any ideas before is start taking this thing apart? Dash lights don't work and fuel guage goes to empty when I turn on the headlights. The other guages don't work anyway and speedo is mechanical so it obviously works. Turn signals also stop working. This truck my wife and her dad built like 20 years ago, it doesn't get driven much and never at night. Except for a couple days ago lol

[oneshotkyle]

Originally Posted by ullose272

Any ideas before is start taking this thing apart? Dash lights don't work and fuel guage goes to empty when I turn on the headlights. The other guages don't work anyway and speedo is mechanical so it obviously works. Turn signals also stop working. This truck my wife and her dad built like 20 years ago, it doesn't get driven much and never at night. Except for a couple days ago lol

I would look for ground problems.

[rockyrivermark]

Follow these steps.
1. Check all the grounds
2. Check all the grounds again.

[dmb]

X2

[Getter-Done]

Check out the Ground clip on the dash in this link.

post #3

Link: https://67-72chevytrucks.com/vboard/...sh+ground+clip

Hope this Helps.

[Mike C]

In addition to checking all the power and ground connections, the rheostat may be bad or dirty on the headlight switch.

[ullose272]

thanks everyone, grounds were my first thought as well

[vics stuff]

X4 like everyone else indicates . Ground issue.
Vic

['68OrangeSunshine]

Don't forget to clean the brass contacts on all the peanut bulb sockets.

When I bought my '71 GMC Jimmy, the dash was completely dead. [Including the speedo.]
PO didn't care, he just cruised with traffic.
Anyway, I got a bunch of fresh bulbs, and cleaned up each twist-in bulb holder -- presto my dash lights came on. Then I found the speedometer cable disconnected in the back. The Water Temp gauge worked with the original engine when I bought it. When I changed to a fresh 350 Mr Goodwrench, the temp sender didn't fit. The repop wouldn't read electrically, so I mounted an Autometer mechanical Water Temp gauge under the dash. Works OK. Stock mech Oil Pressure gauge works OK. Not so sure about the Ammeter -- needle never seems to move off of slightly right of center.
Fuel gauge never worked. I tried running a new wire repacing the Tan line, but no go. Fuel gauge itself is good. Needle points to 3 o'clock when disconnected. It's gotta be the in-tank sensor. I bought a replacement sending unit, but found I have to remove the Skid Shield from under the tank. That means pulling several dozen bolts, after pulling the beefy trailer hitch, to drop the tank. Cutting a small square in the back deck above the sender position is too dicey. Not keen on a blind plunge cut with a cutting blade on a grinder to reach a fuel-filled tank. It could be exciting, but I'm content with monitoring my fuel level by using a logbook on fill-ups and miles driven.

As soon as I had new bulbs in it, the Dash lit up.

[BROWN 70]

x2 post 6. had it happen BROWN 70