Gauge cluster issues

[LTC_]

Having gauge cluster issues on my 89 K1500. Temp and oil pressure not hooked up (need new sensors). Speedo and fuel gauge seem ok, volt meter reads a bit low (between 9 and 14, getting 14.3 at alternator). However, if I turn on the lights and turn up the cluster brightness, the gauges fall and both indicator arrows light up. As I turn the brightness down, the gauges recover back. Also, when driving and using the turn signals, the gauges jump up and down. Where do I start looking to eliminate the issues?

 

[Dale1975]

Have you figured this issue out yet?

 

[Frank Enstein]

Bad ground/bad connection at the connector behind the IP. Pull the contacts out GENTLY just a little bit (go too far and they DIE) and gently clean them with a small wire brush preferably brass. Use some contact cleaner or rubbing alcohol (NOT beer) and a q-tip or 20 to clean after.

Be even nicer to the contacts on the IP skip the wire brush for the IP. They are even more fragile (Not Italian!).

The early model Moon gauges are hard to come by (expensive) if you kill it.

Check the ground strap behind the passenger cylinder head and make sure to clean both the connection at the head and the one at the firewall.

THEN we'll see if you have a problem.

95 percent of my electrical calls are bad grounds and bad connections. Checking the grounds/connections first will save you a bunch of time.

 

[LTC_]

Check the ground strap behind the passenger cylinder head and make sure to clean both the connection at the head and the one at the firewall.

THEN we'll see if you have a problem.

95 percent of my electrical calls are bad grounds and bad connections. Checking the grounds/connections first will save you a bunch of time.

Okay, so there is no ground strap to the firewall. There is a ground strap from the front of the PS head to the frame. Nothing at the back.

 

[Frank Enstein]

Run around the engine compartment with a bunch of ground straps/10 gauge wire with ring connectors and add a few. 3-4 hundred should be enough!

 

[1ton-o-fun]

When I win the lottery, I'm gonna pull an Opra... You get a Big 3 and 4 high kit, you get one, YOU get one, EVERYBODY on GMT400 gets one!!!

@5vortec7 will have to hire a helper or two, lol!

 

[AK49BWL]

I'm in!

 

[LTC_]

What's the bolt size for the back of the head? I can add a strap if I can figure out what size bolt I need.

 

[PlayingWithTBI]

What's the bolt size for the back of the head? I can add a strap if I can figure out what size bolt I need.

IIRC they're all 3/8" NC bolts with 9/16" heads. They'll be the same size as the bolts holding your accessory brackets on the front since the cylinder heads are reversible from side to side.

 

[LTC_]

IIRC they're all 3/8" NC bolts with 9/16" heads. They'll be the same size as the bolts holding your accessory brackets on the front since the cylinder heads are reversible from side to side.

Thank you, I'll see if I have one laying around.