1994 Chevy Silverado speedo

Tiny
FLORIDAROB130
  • MEMBER
  • 1994 CHEVROLET SILVERADO
  • V8
  • 4WD
  • AUTOMATIC
  • 170,000 MILES
I changed the backlight bulbs in the instrument cluster that were burnedout, now the speedodometer does not work, the other cauges work and the lights I put in do not work. It is not a cable speedodometer, so I am at a loss. Help please.
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Friday, April 16th, 2010 AT 5:34 PM

3 Replies

Tiny
MERLIN2021
  • EXPERT
Speedometer & Odometer Do Not Operate Properly

Page 1 of 1
1.Unplug VSS buffer, located under passenger side end of instrument panel. Turn ignition on. Check for battery voltage between harness connector Brown wire and ground. If battery voltage exists, go to next step. If battery voltage does not exist, repair short or open in Pink/Black wire. 2.Check for battery voltage between Brown wire and Black/White wire at harness connector. If battery voltage exists, go to next step. If battery voltage does not exist, repair open in Black/White wire. 3.Raise and support vehicle with drive wheels off ground. Start engine. Shift transmission to Drive. Check for AC voltage between Purple/White and Light Green/Black wires of harness connector. 4.Voltage should change as wheel speed increases or decreases. If AC voltage does not exist, check for short or open in Purple/White and Light Green/Black wires. If wiring is okay, replace vehicle speed sensor. 5.Turn ignition off. Reconnect VSS buffer. Start engine. Put transmission into gear. Backprobe Blue/Black and Black/White wires at VSS buffer connector. If AC voltage varies with RPM change, replace VSS buffer. 6.Backprobe Red/White and Black/White wires at VSS buffer connector. If AC voltage varies with RPM change, replace VSS buffer. If all foregoing checks are okay, replace instrument cluster.
4/16/2010


http://www.2carpros.com/forum/automotive_pictures/62217_Cluster_Conn_1.jpg



http://www.2carpros.com/forum/automotive_pictures/62217_Cluster_Pins_1.jpg


Vehicle speed sensor buffer receives and conditions AC voltage pulses, then sends them to cruise control module, Powertrain Control Module (PCM) and speedometer. Buffer is located behind instrument panel, above glove box.
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Friday, April 16th, 2010 AT 7:35 PM
Tiny
FLORIDAROB130
  • MEMBER
Well I am not equipted to take on the task you advised me of. I really think that the answer is much simpler than you tell me. I moved the dash bulbs I replaced and changed sides, the side that was working now is out and the side that was out is now working, I think I may have damaged the printed circuit board or a fuse. Does the speedo have a separte fuseor circuit?
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Saturday, April 17th, 2010 AT 12:13 PM
Tiny
MERLIN2021
  • EXPERT
The answer to that is in my first post and even shows you the pin to test. If you damaged the printed circuit, get a new cluster at a junkyard and save a lot of time and aggravation. Get the vss buffer above the glove box while your there.
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Saturday, April 17th, 2010 AT 6:39 PM

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