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Interior Discuss upholstery, trim, gauges, etc. No audio & electronics please.

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Old 04-28-2019, 10:06 PM   #1 (permalink)
terryk
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Tach reads low

I had a strange one today. Cruising along towing the 5th wheel, I looked at the tach and it was reading 600 rpm too low. We stopped for fuel, fired it up and itís been correct ever since.

Anyone ever see this?

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Earl's trans cooler, Longs Power Steering Cooler
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NuWa Hitchhiker II LS 29.5LKTG 5th Wheel (11klbs)

Last edited by OkDually; 04-28-2019 at 10:21 PM. Reason: prefix
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Old 04-29-2019, 05:16 PM   #2 (permalink)
64bawagon
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Probably a bad stepper motor in the cluster.

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Old 04-29-2019, 05:20 PM   #3 (permalink)
terryk
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Quote:
Originally Posted by 64bawagon View Post
Probably a bad stepper motor in the cluster.
MIght be. Hasnít done it again. Weíll see.
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2005 Chevy Silverado 3500LT SRW D/A CC/LB LLY 4x4 (loaded)
LBZ MP, TxCAI, Stack sealing, Mass/IAT shield, LML manifold
Edge Insight CTS/EGT/EOT
E837 HD Radiator w/EOC + E837 Secondary Cooling Radiator w/fan, factory air dam
Earl's trans cooler, Longs Power Steering Cooler
GM Severe Duty brake rotors (SD suffix)
NuWa Hitchhiker II LS 29.5LKTG 5th Wheel (11klbs)
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Old 05-06-2019, 09:25 PM   #4 (permalink)
ktmrfs
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up through at least 2006 or so while it isn't common, it also isn't unusual for stepper motors for the gauges to fail. Tach, spedo are often the first to fail. Common failure more is the become occasionally eratic, stuck at odd positions etc. but recover when power is cycled. Eventually they then go completely south.

Now, that's the "bad" news. go on ebay and there are many sources for complete set of replacement stepper motors or sites that will repair an existing cluster. If you have decent soldering skills, easy to do yourself. And as long as the cluster is out you may as well replace ALL the stepper motors, the new ones are a much better design. And given the age, go ahead and replace all the bulbs as well.

the kits come with instructions, but it's pretty obvious. you will need to pull the guage needles, mark with tape where the should be at rest.
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Last edited by ktmrfs; 05-06-2019 at 09:26 PM.
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Old 05-07-2019, 08:55 AM   #5 (permalink)
64bawagon
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The desolder of the old motors is a crucial part of replacing the motors. Desoldering braid works well but you have to be careful with the amount of heat you apply so you dont damage the pads on the PC board.
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Old 05-07-2019, 10:20 AM   #6 (permalink)
terryk
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I am surprised that the reading was offset by 600 RPM. At first I was thinking the needle slipped but since it still read zero when off that wasn't likely. I figured a bad stepper would either be dead or erratic, not offset.

Either way, I've fully expected to have to replace the steppers so that is no big deal. Once any of the gauges finally go south enough to motivate me, I'll do all of them.

Thanks for all of the input!

TK
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2005 Chevy Silverado 3500LT SRW D/A CC/LB LLY 4x4 (loaded)
LBZ MP, TxCAI, Stack sealing, Mass/IAT shield, LML manifold
Edge Insight CTS/EGT/EOT
E837 HD Radiator w/EOC + E837 Secondary Cooling Radiator w/fan, factory air dam
Earl's trans cooler, Longs Power Steering Cooler
GM Severe Duty brake rotors (SD suffix)
NuWa Hitchhiker II LS 29.5LKTG 5th Wheel (11klbs)

Last edited by terryk; 05-07-2019 at 10:21 AM.
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