Gauge cluster erratic

GM Guy

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#1
Make
Chevy
Model
Venture
Year
2004
Miles
76,000
Engine
3.4L
2004 Chevy Venture LS model, 76k mi.
Speedometer and temp gauges are acting flaky. Speedometer is jumps while accelerating or cruising and doesn't read 0 when standing still.
Wife says the temp gauge doesn't come up to normal reading when van is warmed up.( I need to connect my laptop to it to verify that the thermostat is opening at the correct temp).

I learned long ago, that when an electrical problem is acting strangely, it's usually a poor ground issue. Not working entirely, usually a power issue. Any help on locating ground connections associated with the gauges? Any suggestions?
 

grcauto

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#2
Pull the cluster and solder the grounds as well as any cold solder joints.
 
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#3
Father-in-laws 86 electronic dash went off before the one year 12K warranty, dealer replaced it under warranty. He drove a lot, 7 months hit 12K, went off again, dealer want 800 bucks to replace it, that would be closer to $2,000.00 to day, we are getting robbed with inflation.

He drove up 300 miles to see me, couple of voltage checks, problem was on his ignition switch, had its own terminal. EPA banned electrode plating in this country, copper contacts were brown, copper oxide, darn good insulator.

Took is ignition switch apart, flattened that pointed terminal, buffed it like a mirror and added a corrosion resistant lubricant to it, never had problems with it again.

Dashes also use that ribbon cable with a point contact almost plated end terminals that has to be cleaned.

Newest problem with electrical connectors is crap made in China, don't get me started on this. We are not saving money buying crap from China, but importers are making billions with this crap.
 
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#4
a memory was refreshed when I saw the speedo acting weird and not zeroing....

A alternator diode issue had caused erratic speedo - I just felt compelled to add that...... so easy to check.
 

GM Guy

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a memory was refreshed when I saw the speedo acting weird and not zeroing....

A alternator diode issue had caused erratic speedo - I just felt compelled to add that...... so easy to check.

Hmmm. I didn't think of that, probably because the battery's state of charge is not in question. It would be very easy, though, to put my Fluke on ac scale and measure the ac leakage.
I have a feeling the problem is accessory power related. The symptoms are intermittent and seem to be present when cold.
The wife said that the hvac controls weren't working at the same time that the speedo was acting up.
Is there a body control module or another type of module that powers up these circuits that I can check out?
 
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#6
We had a 2004 Chevy, was more conventional, even the DRL used a bunch of relays. Heater controls were cable, cheap at NAPA, around ten bucks. Head lamp switch on the turn signal was manual.

This new stuff can drive a guy nuts. 5 BCM's, ECU is under the hood now to save on wire and an underhood fuse relay box, with GM, our relays were made in China, talk about problems.

Finding even 30AWG wire on this new stuff, issuing commands to the BCM, that goes into the fuse relay box so the 16 AWG wires to the headlamps and every thing else are much shorter.

This is what the Cruze ignition relay looked like, super tiny with itty bitty contacts.

https://www.googleadservices.com/pa...hUKEwjAzLHas-zlAhVKYKwKHbwOB8wQ9aACCDc&adurl=

Got some 1/8" spades wired together so I could pull the relay and jumper the contact pins so I didn't have to call a toll truck.
 

GM Guy

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#7
Hmmm. I didn't think of that, probably because the battery's state of charge is not in question. It would be very easy, though, to put my Fluke on ac scale and measure the ac leakage.
I have a feeling the problem is accessory power related. The symptoms are intermittent and seem to be present when cold.
The wife said that the hvac controls weren't working at the same time that the speedo was acting up.
Is there a body control module or another type of module that powers up these circuits that I can check out?
UPDATE:
I drove this van over the weekend. The only issue is that the speedometer reads faster than actual and doesn't zero out at a stop. After driving several miles with it reading high, and with the engine/cabin at normal operating temp, I stopped the van and restarted it, verifying that the speedometer read zero while at a stand still. The speedometer read correctly after that.

Any ideas on this?