02 Silverado, speedo and tach were jumpy before, now they just don’t work. I’ve checked and fixed both grounds on the wire harness. I checked the A2 and A3 pins on the connector with the truck running and the multimeter says they are getting voltage. I’ve got the cluster mostly apart but can’t really see anything wrong, unless it’s part of whatever is under that inverted and inaccessible black circuit board attached to the main cluster board. No codes. Any help? From A8 (black and white wire) ground to the four connections for the tach and speedo needles, should one of these have ground continuity with everything disconnected? Neither of these has it on any of the four square connectors.
No Speedometer or Tachometer
- Thread starter m3talc0re
- Start date
6716
Member
- Jul 24, 2012
- 836
In the Trailblazer-like vehicles, there are apparently stepper motors that run the gauges, and apparently they go bad after a while. Perhaps it's the same in the Silverado. My oil pressure gauge is dead, voltmeter moves around so much I don't trust it. Speedo has been wonky and then better and then wonky and now better. Might be wonky again later.
You can pull the gauges pack and replace those, or send them out to someone to do for you.
You can pull the gauges pack and replace those, or send them out to someone to do for you.
Mooseman
Moderator
Well yes and no. There was another type of stepper motor from 95 to 02 and then they switched to the newer ones. Your problem may be bad solder joints, which is known to happen on these as the displays go dark or out.
usdashworks.com
A Google search found this place that can rebuild it for you (this is in no way an endorsement or recommendation). You should talk to them first as that page doesn't mention fixing the stepper motors, just the displays.
circuitboardmedics.com
Also found this video that talks about it and should how to fix the jitteryness of the motors:
"S" 95-02 Tach & Speedometer Gauge Air Core Stepper Motor for GMC Truck Cluster - US Dashworks
Brand new production replacement “S” motors, these are a direct replacement for the original yellow colored motors in your cluster now. The “letter code” determines which gauge the motor will replace, the color of the plastic doesn’t make any difference. The original yellow motors use regular...
usdashworks.com
A Google search found this place that can rebuild it for you (this is in no way an endorsement or recommendation). You should talk to them first as that page doesn't mention fixing the stepper motors, just the displays.
1999-2002 Chevrolet Odometer / Gear Indicator Repair
This odometer and or gear indicator repair service covers all vehicles manufactured by Chevrolet between 1999 to 2003.
circuitboardmedics.com
Also found this video that talks about it and should how to fix the jitteryness of the motors:
With some more "Information Goodies and Data" at this Link:
gmtnation.com
Best Complete Diagnostic & Repair Videos for IPC PRND123 Issues on 1999-2002 Full Size GM Trucks
We've all heard the expression "Stepper Motors and LEDs" whenever problems with Instrument Panel Clusters (IPC) raise their Ugly Heads. The same thing goes for the "PRND123" Displays, too as per problems with them "Dimming" or when they inexplicably TURN OFF. But for those of us who own Full...
gmtnation.com
That link is good and I’ll definitely keep it open in another tab, but it doesn’t seem to be the issue for me. With the engine running, I get 6.15v to the engine speed terminal and 12v to the vehicle speed terminal but neither changes with engine rpm. I was thinking maybe it just increased voltage to raise the needles, but I’m wondering if it’s actually pulses of those voltages and my multimeter just isn’t picking up the pulses. The voltages do fluctuate by like 0.1-0.5v on the display, so that’s what I am thinking.
There must be steppers since the diagram below shows all gauges being connected to the Class 2 Serial bus: 2002 Chevy 1500 PU Instrument Cluster schematics
The fluctuations you are seeing on your multimeter are digital data, not analog data (voltage). You would need an oscilloscope to see the digital traffic.
Do you have access to a OBD scan tool that can display RPM? If so, does it indicate a stable RPM? Another option would be to use an app like Torque in conjunction with an ELM327 interface to display RPM & Vehicle Speed.
FWIW... The Final Arbiter of the *Type* of IPC nested in your Dashboard would be to just pull it... and then compare what you can see on the very back and on the INSIDES of the IPC with these attached images.
*IF* they MATCH what is listed below... Then your System relies upon an almost Bullet-Proof Air-Core Style Electro-Magnetic Coil Operated Gauge System that requires they all be filled to the brim inside with an innocuous (but COPIOUS) amount of Commercial Viscous Fluid that will prevent the Dials from spinning past their control points or be jarred by the normal "Vibrations & Gyrations" ever present in moving Pick-Up Trucks..
No matter what the Voltage Measurement Variations are ... No AIR-CORE FLUID?... THEN THAT IS NO GOO-ID!. Without that "GOO" being injected over the Tip of the Spindle Shaft via a Large Hypodermic Syringe inside of each Gauge to Dampen and restrict the variable inputs to the Internal Motors... then the Gauge Spindle Pointers will either *Bounce Around* excessively like *Rubber Balls* ... or NOT respond at all if they are internally BONE DRY and thus, way too far out of position.
It has been a while since I picked up THIS particular IPC depicted below... but my motivations when I first got it were to have as many AIR-CORE Motors and Bulbs (& Boards) on hand as possible. This was because even the After-Market ones can cost as much as $40.00 a piece.
AND... Because the "Message Center" Sealed Black Square Orange Display & Logic Board located in the Upper Left Side of my IPC was NOT working properly and was likewise UNAVAILABLE, getting Used IPCs like this one when they were still Dirt Cheap seemed the best way to Kill a WHOLE Lot of Birds ...with One Stone. So NOW seems like as good a time as any to memorialize all of these images to suit your purposes... and my own. :>)
Notice how the Black Plastic Rear Cover HOLDS the Gray Rectangular Screw Sockets for the Replaceable Light Bulbs from backing out from Excessive Truck Vibrations? Hmmm... VERY Clever Engineering Here... Yes? :>)
View attachment 113168
See Post #3 for Details about the Special Silicone Fluid & Craft Hypodermic Syringes:
gmtnation.com
And HERE is a Reasonably Priced IPC for the 1999-2002 Vintage Chevrolet Silverado 1500s ...via eBay:
*IF* they MATCH what is listed below... Then your System relies upon an almost Bullet-Proof Air-Core Style Electro-Magnetic Coil Operated Gauge System that requires they all be filled to the brim inside with an innocuous (but COPIOUS) amount of Commercial Viscous Fluid that will prevent the Dials from spinning past their control points or be jarred by the normal "Vibrations & Gyrations" ever present in moving Pick-Up Trucks..
No matter what the Voltage Measurement Variations are ... No AIR-CORE FLUID?... THEN THAT IS NO GOO-ID!. Without that "GOO" being injected over the Tip of the Spindle Shaft via a Large Hypodermic Syringe inside of each Gauge to Dampen and restrict the variable inputs to the Internal Motors... then the Gauge Spindle Pointers will either *Bounce Around* excessively like *Rubber Balls* ... or NOT respond at all if they are internally BONE DRY and thus, way too far out of position.
It has been a while since I picked up THIS particular IPC depicted below... but my motivations when I first got it were to have as many AIR-CORE Motors and Bulbs (& Boards) on hand as possible. This was because even the After-Market ones can cost as much as $40.00 a piece.
AND... Because the "Message Center" Sealed Black Square Orange Display & Logic Board located in the Upper Left Side of my IPC was NOT working properly and was likewise UNAVAILABLE, getting Used IPCs like this one when they were still Dirt Cheap seemed the best way to Kill a WHOLE Lot of Birds ...with One Stone. So NOW seems like as good a time as any to memorialize all of these images to suit your purposes... and my own. :>)
Notice how the Black Plastic Rear Cover HOLDS the Gray Rectangular Screw Sockets for the Replaceable Light Bulbs from backing out from Excessive Truck Vibrations? Hmmm... VERY Clever Engineering Here... Yes? :>)
View attachment 113168See Post #3 for Details about the Special Silicone Fluid & Craft Hypodermic Syringes:
Best Complete Diagnostic & Repair Videos for IPC PRND123 Issues on 1999-2002 Full Size GM Trucks
We've all heard the expression "Stepper Motors and LEDs" whenever problems with Instrument Panel Clusters (IPC) raise their Ugly Heads. The same thing goes for the "PRND123" Displays, too as per problems with them "Dimming" or when they inexplicably TURN OFF. But for those of us who own Full...
gmtnation.com
And HERE is a Reasonably Priced IPC for the 1999-2002 Vintage Chevrolet Silverado 1500s ...via eBay:
ð¥99-02 CHEVY SILVERADO SIERRA TAHOE DASH INSTRUMENT GAUGE CLUSTER SPEEDOMETER | eBay
Find many great new & used options and get the best deals for ð¥99-02 CHEVY SILVERADO SIERRA TAHOE DASH INSTRUMENT GAUGE CLUSTER SPEEDOMETER at the best online prices at eBay! Free shipping for many products!
www.ebay.com
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I used my scanner (BlueDriver for the curious) and it shows rpm and vehicle speeds being reported. So I’m guessing the problem is all in the gauge. I think I’m going to remove all the solder from where the connector pins are soldered to the board and redo them. Or at least the engine speed and vehicle speed pins.
So I completely reflowed the solder for where the A2 and A3 pins are connected to the main board. A2 is engine speed and A3 is vehicle speed, I think. Took it for a drive and they’re working now. Seems both of them had micro cracked solder joints.
Yeah, this ain’t it. It didn’t fix it. Idk if the vehicle speed wire may be broken? I have no speedometer right now and the odometer doesn’t increase, either.
If you have an OBD2 adapter (bluetooth or wifi) you can use a phone app like Torque Pro, Car Scanner ELM OBD2, OBD Fusion, etc. to display the speedometer and tachometer readings from the serial data bus.
If they appear OK there then at least you will know the PCM is receiving the neccesary signals from the engine and driveshaft sensors.
The EBCM also gets the VSS signal from the PCM. I don't know if it sets a code for a missing VSS signal though.
Any other warning lamps on?
EDIT: Oops! I was thinking TrailBlazer! Don't know if same conditions apply to Silverado.
If they appear OK there then at least you will know the PCM is receiving the neccesary signals from the engine and driveshaft sensors.
The EBCM also gets the VSS signal from the PCM. I don't know if it sets a code for a missing VSS signal though.
Any other warning lamps on?
EDIT: Oops! I was thinking TrailBlazer! Don't know if same conditions apply to Silverado.
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There is another source for this problem to occur...from Rodent Depredation, proven out as being the Cause and Origin of the problem involving a 2001 Chevrolet Siverado explained in THIS Write-Up on another Forum... with excellent descriptions and these Photos to serve as a guide in this "Seek-Find-Repair":
www.silveradosierra.com
If you mean to tear into these locations, be mindful that if the Old Dust is disturbed, it can harbor The Dreaded HANTA Virus carried in the Feces, Urine and Saliva of Rats and Mice as dried out and lurking therein. If disturbed... the contaminated dust can go airborne and become inhaled or enter the body through the unprotected Eyes, Nose, Mouth, Cuts and Lungs:
There is no efficacious cure or treatment for this illness (HPS) and Death from HANTA can be as high as 40% leaving the survivors with a very poor quality of life after a very long recovery period. Please consider using this Protection Gear and Procedures while working around such areas well before attempting any repairs:
(1) An N-95 Face Mask, Wrap-Around Eye Protection and M-11 Nitrile Gloves.
(2) Use NO Compressed or Canned Air to blow out the Dusty locations. Materials can be infected with Viral Particles.
(3) Clean up Nesting, Feces and Desiccated Urine contamination with Wet Cloths soaked in Warm Water and Bleach.
(4) Dispose of the Nesting and Detritus and clean up materials inside of sealed Zip-Lock Bags.
www.cdc.gov
Tachometer not working
Hello All, I have a new to me, 2001 Silverado 1500 2wd with 165K miles on it. Being 16 years old and 165K+ miles, it has it's share of gremlins that I am slowly fixing. One that has me stumped right now is the tachometer not working. I have read various threads about the instrument cluster and...
www.silveradosierra.com
If you mean to tear into these locations, be mindful that if the Old Dust is disturbed, it can harbor The Dreaded HANTA Virus carried in the Feces, Urine and Saliva of Rats and Mice as dried out and lurking therein. If disturbed... the contaminated dust can go airborne and become inhaled or enter the body through the unprotected Eyes, Nose, Mouth, Cuts and Lungs:
There is no efficacious cure or treatment for this illness (HPS) and Death from HANTA can be as high as 40% leaving the survivors with a very poor quality of life after a very long recovery period. Please consider using this Protection Gear and Procedures while working around such areas well before attempting any repairs:
(1) An N-95 Face Mask, Wrap-Around Eye Protection and M-11 Nitrile Gloves.
(2) Use NO Compressed or Canned Air to blow out the Dusty locations. Materials can be infected with Viral Particles.
(3) Clean up Nesting, Feces and Desiccated Urine contamination with Wet Cloths soaked in Warm Water and Bleach.
(4) Dispose of the Nesting and Detritus and clean up materials inside of sealed Zip-Lock Bags.
Hantavirus Prevention
How to clean up after pet rodents and safely clean up after infestations.
www.cdc.gov
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