Back again!

Ok - Jimmy is running well - no problems there since replacing fuel pump & filter.

Last night my son said that the battery light had came on & the voltage was low. He said he sat there a while & it then came up.
(He was also late coming home & was at his girlfriends' house so I figure they were sitting in her driveway listening to music & playing 'smacky face' until the battery was nearly dead... but anyhow...)

Tested it with my dvm this morning & battery (engine off, key off) showed about 12.3v.
I started it & the battery light went off as it should; but the cluster voltage gauge did stay low... then took about 5 seconds to reach it's normal (factory innacurate) range.
I tested the battery voltage again (engine running) & it was showing about 13.6v so it's charging.
A restart showed the same 'slow rise' on the voltage gauge.
All other gauges appear normal.

Battery and alternator both were replaced this past summer.

Has anyone else had their voltage gauge start acting this way?

I'm thinking that maybe the gauge 'motor' is starting to get sticky the way my Express van speedo 'sticks'... but short of pulling the cluster don't know any other way to check it.

While I'm at it... what is the correct name for the 'motors' that drive the gauges in the cluster? I know I saw them on evilBay once... but don't know what to search for now.

 

The alternator field is driven by the PCM in these trucks. There are a number of things that could cause the PCM to delay activating the field. If it comes up within 10 seconds of starting the truck, I wouldn't be all that concerned with it.

I reposted a how-to on changing it from PWM (pulse width modulated) from the PCM to battery reference. It is in the Tech Article section if you are interested in seeing if that changes how the alternator reacts.

The cluster gauges are run by stepper motors.

 

With everything else happening I forgot about this post - oops.

Had this recur tonight with me (I had son's GMC working on it).

Before working on it tonight I saw no obvious problem with charging etc. Repaired his hub assembly then lowered jack. Restarted it & at that point the instrument cluster showed 9v & battery light was on. ( ! ) Grabbed a meter & actual voltage with dvm measured about 14.5 volts with or without headlights.... at idle or revved up.

It was previously slow to come up on the voltage gauge before but gauges did not recover after 15+ minutes of engine running tonight. My son also let me know (I don't drive it) that it will do this sometimes & then will be ok.


Thanks for posting that swartlkk, I'll go check it out & hopefully can see what is happening with this thing.

 

Found the tech thread... but couldn't get the picture links to open - nothing but thumbnails & can't enlarge them without pixelating the details. Is there a direct link to the pages?

 

Today my son started it up & the darn thing is acting like nothing happened. No battery light & normal voltage on gauge. He also informed me that it has done this before so it's an intermittent issue - maybe with the cluster, dunno.

Might be unrelated but there also was a faint, intermittent clicking/gurgling sound coming from the area of the radio last night after I test drove it. I had a 97 Blazer that sounded like a teletype machine from same area & never did figure out what the hell that was.

 

I appreciate the help - few problems with the tech pages mentioned, though:


https://blazerforum.com/forum/tech-a...em-test-36792/

The picture links are broken. The only thing is visible are the thumbnails & you can't enlarge them without pixelating the details.

Is there a direct link to the alternator test page images?

and

https://blazerforum.com/forum/tech-a...ference-60425/


Parts source listed is a dead URL: http://www.pcsconnectors.com/