'02 Tahoe dash light question

**Milo'sTahoe** · 06-14-2009, 12:32 AM

New to the website and could use your help. Every once and a while the gear shift indicator/odometer area on my dash will pulsate w/ the idle while my tahoe is parked, engine running at idle. The instant I drive, ie: accelerate away, the pulsation of the light goes away and stays solid like the dash normally does. My tahoe has 114K, new battery and the cables are clean. The dash cluster, to my knowledge, has not been replaced, but all guages function properly. Do I need a new alternator, can i assume my voltage regulator, in the alternator, is going south? Thanks for your help. Milo

**Springthing** · 06-14-2009, 12:39 AM

That was my thought as I was reading the post. If the battery is new then that's counted out but I'd have the alternator checked (or check it yourself) to see how it's holding up. Could be that it's bouncing the amps enough to make the dash lights pulsate.

**2ToNe04** · 06-14-2009, 06:12 AM

your clusters lights might be wanting to go out.

**Milo'sTahoe** · 06-16-2009, 10:01 AM

Ok, thanks guys...

**Z71_guy** · 06-16-2009, 01:24 PM

i would have to bet on an alternator but get it tested to make sure

**Milo'sTahoe** · 06-22-2009, 09:15 PM

OK, so I grabbed a new alternator (130 Amp Reman) and put it in. Now all the lights on my guage cluster pulsate at idle, all the time, and my voltmeter actually shows a dip in voltage every time the guage lights pulsate. It used to be before the odometer/gear shifter would only pulsate sometimes, but not normally on start up or just basic warm up idle, and the rest of the guages did not pulsate. This new alternator has the guages pulsating from the very first turn of the key.

So...if the new alternator I bought is good, do I have a bad guage/speedometer cluster? Did I get a bad reman alternator or is the alternator fresh and the old guage cluster can not handle the extra/full power the new alternator is dishing out.

I put the original alternator back in, the pulsation went away for now and all the guages are acting normal. I am sure at some point the gear selector/odometer will begin to pulsate at idle again, but for now all the guages are working fine. What do you guys think?

**Jimmiee** · 06-22-2009, 10:13 PM

One reason the dash lights are acting wired may be your ignition switch is about to go out. These are the first warning signs. This was a very common problem on 90's vintage Chevy Trucks. Keep this in mind next time they act up.

**Milo'sTahoe** · 06-24-2009, 12:45 PM

did chevy have the same problems with the newer ignition switches in the 99 and up tahoes and silverados? I actually had that switch go out in a '00 silverado w/ 3k miles on the odometer, once the switch was changed it worked great ever since. But it gave me no warning, it just went.

Do you think my contacts on the ignition switch are worn down to a point that I should just replace it? I think I might have another warning sign. Every once and a while I will turn the ignition off after driving it and the driver info center yellow security light does not instantly start blinking like it usually does, and I will here a clicking sound (one or maybe two) coming through the speakers. Then when i open the door the yellow secuity light will come on. My truck is optioned out with the auto climate control and I thought maybe the door sensor might be going out, but maybe it is the ignition switch. I have had a dealer check it but of course they could not replicate the issue, and I do understand that.

Thanks for your feedback, Myles

**Milo'sTahoe** · 08-06-2009, 09:59 AM

Well I finally got around to working on this problem. The issue with my dash light pulsation came back to the alternator being worn out, but it was actually the rectifier bridge in the alternator that was bad. I spoke with a buddy of mine who is a mechanic and he advised right on the spot that he thought my problem was this rectifier bridge. He says when i put in the remanufactured alternator, and all my dash lights were pulsating and the voltometer was pulsating, that got him to realize the rest of the alternator may have been fine, but the rectifier bridge in the reman alternator must have been worn out. He said buy a new alternator and you won't have the issue, I did and my Tahoe runs great and has no dash light issues.

It was definitely worth the $50 more to get the new alternator than the reman...Myles

**pmf608** · 08-06-2009, 12:33 PM

Im glad you got that fixed. getting stuck with a bad alternator is crappy.

My mom's Buick Lucerne does this same sort of thing - only if you use an accessory at idle though. I think the alternator is just underpowered on that car because if you use one of the power windows while its idleing, the lights will dim, the rpms drop, and you can feel the difference in the car - until the circuit breaker cuts power to the window when its fully up or down. The more windows you use at once, the more the difference.