Instrument cluster needles bouncing
09-16-2012, 02:52 PM
#1
Instrument cluster needles bouncing Has anyone seen their gauge needles start bouncing, and/or the check engine light come on when all the gauges look ok? Please take a look at these videos and tell me what you think.
http://s808.photobucket.com/albums/z...0916-00008.mp4
http://s808.photobucket.com/albums/z...0916-00007.mp4
http://s808.photobucket.com/albums/z...0916-00006.mp4
http://s808.photobucket.com/albums/z...ilpressure.mp4
The oil pressure gauge will flicker like that also, but usually only when accelerating slowly from idle.
http://s808.photobucket.com/albums/z...0916-00008.mp4
http://s808.photobucket.com/albums/z...0916-00007.mp4
http://s808.photobucket.com/albums/z...0916-00006.mp4
http://s808.photobucket.com/albums/z...ilpressure.mp4
The oil pressure gauge will flicker like that also, but usually only when accelerating slowly from idle.
09-16-2012, 03:37 PM
#4
Crap. I just had one rebuilt locally maybe a month ago. It developed a squeal the first day after a good rain. I found that the mounting bolts had worked themselves loose and the pulley was wobbling. We tightened both up on a lift Friday, but it squealed on a cold start yesterday morning. The belt is very tight.
Edit: I ran an errand tonight and the CEL was intermittently on even when the voltage gauge read above 13V..?
Edit: I ran an errand tonight and the CEL was intermittently on even when the voltage gauge read above 13V..?
Last edited by JimMueller; 09-16-2012 at 06:00 PM.
09-17-2012, 02:05 PM
#7
cel = check engine light.
I swapped the alternator for a spare I keep from AutoZone and the gauges & CEL keep doing the same thing. I dropped off the old alternator at the shop and they noticed that there was a small bit of melted plastic, a thin line like perhaps a wire looks to be the cause. The terminal boot which was previously on there was torn and I wasn't able to re-use it so I didn't have one on the terminal. The shop called me back and advised the extra heavy duty regulator they put in last time had died; they replaced the regulator and the pulley. Said it was running fine at 115A, ready for pickup.
After I was driving on the temp alternator, the gauges first bounced over a rough patch of pavement... any chance this is a short and/or grounding issue?
I swapped the alternator for a spare I keep from AutoZone and the gauges & CEL keep doing the same thing. I dropped off the old alternator at the shop and they noticed that there was a small bit of melted plastic, a thin line like perhaps a wire looks to be the cause. The terminal boot which was previously on there was torn and I wasn't able to re-use it so I didn't have one on the terminal. The shop called me back and advised the extra heavy duty regulator they put in last time had died; they replaced the regulator and the pulley. Said it was running fine at 115A, ready for pickup.
After I was driving on the temp alternator, the gauges first bounced over a rough patch of pavement... any chance this is a short and/or grounding issue?
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09-21-2012, 02:32 PM
#9
OK, I described it wrong. It was the check gauges light, not the check engine (SES) light. A prior exciter wire repair included a new terminal which was too small for the wire gauge, so they cut/bent the extra wires away. The terminal was replaced with the proper size today and so far the gauge light and bouncing needles have disappeared.
09-28-2012, 06:20 PM
#10
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Try the grounding circuit that is common to both gauges f you haven't removed the cluster and looked for loose conections or broken wire paths(I don't know exactly what is there as I haven't had mine out yet) it is the first place I would look also ckeck the wires in the connectors are fully seated.
below is from the GM website the same one the dealers use
The speedometer displays vehicle speed in miles per hour (MPH) or kilometers per hour (KPH). Voltage pulses from the Powertrain Control Module (PCM) are interpreted by solid state logic circuits within the cluster. The solid state circuits process the pulses and output a signal to drive the speedometer pointer. For further information regarding the speedometer, refer to Engine Controls.
The tachometer displays engine speed in Revolutions Per Minute (RPM). Voltage pulses from the electronic ignition control module (V6 VIN K) or the powertrain control module (V8 VIN G) are interpreted by solid state logic circuits within the cluster. The solid state circuits process the pulses and put out a signal that drives the pointer of the meter. The pointer is moved with magnetic fields created from coils within the tachometer.
below is from the GM website the same one the dealers use
The speedometer displays vehicle speed in miles per hour (MPH) or kilometers per hour (KPH). Voltage pulses from the Powertrain Control Module (PCM) are interpreted by solid state logic circuits within the cluster. The solid state circuits process the pulses and output a signal to drive the speedometer pointer. For further information regarding the speedometer, refer to Engine Controls.
The tachometer displays engine speed in Revolutions Per Minute (RPM). Voltage pulses from the electronic ignition control module (V6 VIN K) or the powertrain control module (V8 VIN G) are interpreted by solid state logic circuits within the cluster. The solid state circuits process the pulses and put out a signal that drives the pointer of the meter. The pointer is moved with magnetic fields created from coils within the tachometer.
