Need help with my truck

[sb47]

I have a 1994 silverado 1/2 ton. My gauges dip when I put my blinker on. The fuel gauge oil and speedo all dip when the blinker is on. It has a new alt, and battery so I don't think that is it. It charges fine at 13v. I'm thinking the blinker module may be going bad. Chassy grounds are all good. Any other ideas whats going on with it?

 

[pioneerguy600]

Check all the electrical grounding points. Body to engine block is very important.

 

[sb47]

Check all the electrical grounding points. Body to engine block is very important.

Already checked that. I even added more grounding points awhile back. No change.

 

[Fatherwheels]

An indicator module should be cheap enough, swap out the old with a new one,
there is very little else other than the indicator switch / stick shorting out, disconnect
the indicator module and flick the stick to see if it still dims the other gauges, if not then
its not the stick, its the module.

 

[trains]

first thought is whats already been mentioned, especially a poor earth.
I would also offer checking any wiring loom connect point for corrosion where the male/ female pins and sockets join each other.
Start from the loom from the indicator switch where it joins the main loom, then trace from there, but usually its on that first join.

 

[knockbill]

Poor grounds or loose/corroded connections are the first thing to check,,, I pulled teh dash on my 86 Dodge for the same problem, cleaned and tightened all plugs/jacks/bolts,, Some cars have dash voltage regulators, 5v I believe, to keep the gauges accurate if `the 12v supply sags (AC cycling, etc)

 

[Clyde85]

Could it be the gauge cluster it's self?

 

[J D]

The gauges can be regulated at just about any voltage depending on what the manufacturer wants to do to keep their stuff proprietary. I would suspect the gauges & flasher are all powered by the same circuit & when the indicators are on it's drawing more current than the wiring can supply. Unlikely to be a faulty component as the amount of current to cause a voltage drop on good wiring would cause the fuse to blow.
Start by finding said fuse (it may even be the problem). Take a multimeter set to volts & measure the voltage on the fuse whilst the fault is present. If normal (12V) then wiring to fuse is good... Test wire leaving fuse... Wire entering dash... Etc... Etc...
Alternatively you can test the earth side of the circuit the same way, but you'd be looking for Voltage that shouldn't be there on what should be an earth wire.
The most likely scenario is that there is a poor earth to the guage circuit & it is finding earth through the blinker bulbs instead, when the blinkers are powered that earth disappears & your gauges play up. Do the blinker lights on the dash light up as brightly as they should?

 

[J D]

Could it be the gauge cluster it's self?

Yep, or the connection to it

 

[J D]

It charges fine at 13v.

13V is low for charging... That won't be the cause of your problem, but a good alternator should be charging at 14V give or take about half a volt. Might just be your meter though

 

[cookies]

Check the Battery cables, pull back the rubber covers, remove their bolts and check their resistance from end to end disconnected. Those old GMs with side mount battery terminals are NOTORIOUS for battery acid seepage into the terminals and wiring.

 

[sb47]

The gauges can be regulated at just about any voltage depending on what the manufacturer wants to do to keep their stuff proprietary. I would suspect the gauges & flasher are all powered by the same circuit & when the indicators are on it's drawing more current than the wiring can supply. Unlikely to be a faulty component as the amount of current to cause a voltage drop on good wiring would cause the fuse to blow.
Start by finding said fuse (it may even be the problem). Take a multimeter set to volts & measure the voltage on the fuse whilst the fault is present. If normal (12V) then wiring to fuse is good... Test wire leaving fuse... Wire entering dash... Etc... Etc...
Alternatively you can test the earth side of the circuit the same way, but you'd be looking for Voltage that shouldn't be there on what should be an earth wire.
The most likely scenario is that there is a poor earth to the guage circuit & it is finding earth through the blinker bulbs instead, when the blinkers are powered that earth disappears & your gauges play up. Do the blinker lights on the dash light up as brightly as they should?

Yes the indicator lights flash normally as they always have however, The clicking noise that a typical blinker makes is weak and I can barely hear it.I am old and hard of hearing but that may be indicating the flasher module is weak or going bad. A new flasher module is a cheap thing to try and I will do that on my next trip to the auto parts store.
It started with just the fuel gauge doing the dip dance but now the oil and speedo are starting to do it as well. That tells me the problem may be getting worse.

 

[CentaurG2]

What? A GM instrument cluster not working right? Say it aint so. On my truck, all gauges are intermittent. It depends on the trucks mood what gauges it wants to have working on any given day or time. I would replace the turn signal relay. If that don’t fix it, it is most likely in the cluster itself. If you pull the panel out, there are companies that repair newer trucks for $75-150. I don’t know of a company that works on older stuff but they might be out there. I probably would just put up with it.



GM Gauge Cluster Repair, GM Instrument Cluster, Speedometer Repair (gmgaugerepair.com)

 

[cookies]

The older clusters rarely ever failed but 99 and newer are junk, thats why I suggested checking the cables, terminals and grounds. I would also suggest getting that new alternator tested for a failed diode. Its also not uncommon to have a failed fuel level sending unit but multiple wonky gages points to what I first suggested.

 

[holeycow]

I worked with a cat foreman in the bush who had his instrument cluster in his lap about 4 times on one job, This was about a 1 or two year old pickup in about 2006? Cluster failures were common. The boys had them figured after some trial and error. PITA.

So I concur with cookies.

I like cookies!

 

[J D]

If the alternator or battery/terminals was the issue you'd have issues whenever any high drain load (lights/heater/wipers/ect) was in use

 

[cookies]

If the alternator or battery/terminals was the issue you'd have issues whenever any high drain load (lights/heater/wipers/ect) was in use

not necessarily, I fixed plenty of crusty battery terminal bolts, eyelits and replaced cables on chevys that would crank and run but had wonky gages, flickering lights, fluxuating blower motor output etc that solved the gremlins...those side post batteries caused electrical problems because batteries vent around the terminals and when mounted on the side its much worse.

 

[siouxindian]

Already checked that. I even added more grounding points awhile back. No change.

yes . well you got a bad ground... you got a bad ground. old people know but sometimes we wrong also .you got a bad ground. check the back of the gauge panel . seen it before .

 

[J D]

not necessarily, I fixed plenty of crusty battery terminal bolts, eyelits and replaced cables on chevys that would crank and run but had wonky gages, flickering lights, fluxuating blower motor output etc that solved the gremlins...those side post batteries caused electrical problems because batteries vent around the terminals and when mounted on the side its much worse.

Maybe I should have said "unlikely".
I do agree with you when it comes to newer vehicles where everything is microchip controlled talking can-bus, the voltage fluctuations caused by poor connections can create havoc. I'm not particularly familiar with the Silverado but would expect it to be more of a "traditional" type of dash.

 

[sb47]

The older clusters rarely ever failed but 99 and newer are junk, thats why I suggested checking the cables, terminals and grounds. I would also suggest getting that new alternator tested for a failed diode. Its also not uncommon to have a failed fuel level sending unit but multiple wonky gages points to what I first suggested.

My 12v charger has a battery check function and a alt check function, both check out ok. I'm not going to dig to deep into it until the summer heat wave settles down a bit. 100+ right now. To freaking hot to dig into something that can wait a bit.