Alternator Question

[duramaxdude]

MY volt gauge on my truck goes up and down at random times. It will go from 14 down to I think around 11 and the odd time it will go up to 14 again. I havent noticed any starting problems or lights dimming the gauge just jumps around. It will also pick its random spot to sit at.

 

[Odlaw]

Mine does the same thing....it's gotten worse lately. I'm gonna pull the cluster out tomorrow and see if there is anything I can do to clean the contacts.

welcome to GM

 

[WarWagon]

Plug in a real voltmeter somewhere, like cig lighter, and see if the system is really doing that or bad gauge/wiring/contacts.

 

[duramaxdude]

I went and hooked up a volt metre onto the batteries and they do charge 14 volts. Would anybody know were the gauge gets its voltage reading from.

Also while I had the hood poped and had the motor running the A/C compressoe kicked on and off. when I shut the fan off it wouldn't do it anymore. I took the ralay out for it but is it supposed to do that.

 

[jmiller]

I went and hooked up a volt metre onto the batteries and they do charge 14 volts. Would anybody know were the gauge gets its voltage reading from.

Also while I had the hood poped and had the motor running the A/C compressoe kicked on and off. when I shut the fan off it wouldn't do it anymore. I took the ralay out for it but is it supposed to do that.

If your defrost is on, the A/C cycles once the truck warms up some. Its used to dehumidify the air. Clears your windows faster.

Check your ground, dirty and corroded ones causes funny things to happen. Also look at the voltage at different places. Cigarette lighter, battery, alternator output, Instrument panel fuse block. Try pick a common ground point when you check each point, this will help with determining a ground or dirty connection. Also change the electrical load, head lights on off, fan on off.

 

[duramaxdude]

If your defrost is on, the A/C cycles once the truck warms up some. Its used to dehumidify the air. Clears your windows faster.

Check your ground, dirty and corroded ones causes funny things to happen. Also look at the voltage at different places. Cigarette lighter, battery, alternator output, Instrument panel fuse block. Try pick a common ground point when you check each point, this will help with determining a ground or dirty connection. Also change the electrical load, head lights on off, fan on off.

I will try my voltmetre at different locations today. It dosent matter if you fool around with the light or the fan it still dosent make the gauge change. I noticed today the when I slam on the dash ontop of the gauge it will bring it up to 14 for a bit.

Good to know about the A/C. Thanks

 

[duramaxdude]

Where do the wires go for the volt metre.

Also it must be the gauge because every were I test I get 14 volts.

 

[Odlaw]

I will try my voltmetre at different locations today. It dosent matter if you fool around with the light or the fan it still dosent make the gauge change. I noticed today the when I slam on the dash ontop of the gauge it will bring it up to 14 for a bit.

Good to know about the A/C. Thanks

Yeah, the whack on top of the dash will make mine do that too....more than likely it's the contacts on the back of the cluster...or the gauge. Mine read 14.28 volts every where I checked. I just cleaned all my grounds 6 months ago...it didn't help.

 

[WarWagon]

I will try my voltmetre at different locations today. It dosent matter if you fool around with the light or the fan it still dosent make the gauge change. I noticed today the when I slam on the dash ontop of the gauge it will bring it up to 14 for a bit.

Good to know about the A/C. Thanks

Now you know the gauge and related contacts are the issue. The "thump it twice" is moving a corroded, burnt, or loose contact to a better area it can conduct. A perfect example is a cracked solder joint where the arching causes a high resistance point. Vibration can move the parts and overcome the open or high resistance circuit by resting on a better part of the cracked conductor. Same applies to a plug in connector.

 

[duramaxdude]

Yeah, the whack on top of the dash will make mine do that too....more than likely it's the contacts on the back of the cluster...or the gauge. Mine read 14.28 volts every where I checked. I just cleaned all my grounds 6 months ago...it didn't help.

Mine read 14.20 (same thing). If I get around to it tomorrow I will pull my gauge cluster of and look at it. Hopefully we can get it going on both our trucks. Could be handy to have if the Alternator does go out.

 

[Odlaw]

Well, it rained all day yesterday and I don't do a whole lot on Sundays unless my ass is in a ditch.....or is that ox...I'll have to check the scriptures again....anyway, I'll be celebrating MLK day tomorrow by (hopefully) removing the cluster to check it out.

I'll keep you posted.

 

[duramaxdude]

I couldnt get to it today.

We were out fishing and man we went to three lakes and they were all dead. There is no place to fish around here all the lakes are dead.

Well I should get at it tomorrow. I cant drive anywere I got no money for fuel. Been trying to find a job but its kindoff hard when your 16 and going to school.

I will get at it most likely when I come home from school tomorrow and let you know how I did.

 

[duramaxdude]

Well I had nothing to do after supper so I decided to pull the gauges off and have a look. When I had it out I noticed that all my contacs were nice and clean. I looked at the volt gauge conections and noticed the tabs were bent up alittle. All I did was take two small screwdrivers and gently pushed them down so they made good contact. Now it works just perfect. Started it up drove it for a bit around the yard and its all good now.

Hope this helps someone.

 

[Odlaw]

Well I had nothing to do after supper so I decided to pull the gauges off and have a look. When I had it out I noticed that all my contacs were nice and clean. I looked at the volt gauge conections and noticed the tabs were bent up alittle. All I did was take two small screwdrivers and gently pushed them down so they made good contact. Now it works just perfect. Started it up drove it for a bit around the yard and its all good now.

Hope this helps someone.

Good deal!

I pulled mine apart today and did the same thing plus, I noticed those little square looking contact things on the back of the cluster were all worked out and a couple of them were barely making contact with the circuit. They're the press in type so I just pressed em in some ....all of them went in flush and appear to be making good contact now. I'm showing just a hair under 14v on the gauge when it is actually 14.2 - i can live with that. It's better than always reading 10-12 volts and jumping all over the place.

Now, the only problem I have is after I reinstalled the cluster now my temp gauge acts like it wants to stick. Drove it until it warmed up good and it only move one tick from the bottom, whacked the top of the dash and it jump up to around 170. Shut the truck off, and went out and cranked it a few minutes ago (cold) and it is still stuck on 170.......geez

 

[ak diesel driver]

2 steps forward 1 step back

 

[duramaxdude]

Good deal!

I pulled mine apart today and did the same thing plus, I noticed those little square looking contact things on the back of the cluster were all worked out and a couple of them were barely making contact with the circuit. They're the press in type so I just pressed em in some ....all of them went in flush and appear to be making good contact now. I'm showing just a hair under 14v on the gauge when it is actually 14.2 - i can live with that. It's better than always reading 10-12 volts and jumping all over the place.

Now, the only problem I have is after I reinstalled the cluster now my temp gauge acts like it wants to stick. Drove it until it warmed up good and it only move one tick from the bottom, whacked the top of the dash and it jump up to around 170. Shut the truck off, and went out and cranked it a few minutes ago (cold) and it is still stuck on 170.......geez

What could have happened was the conact for the temp gauge got pushed in to far. If you ever have a chance try pulling it back some and moving the contacts down.

Just a thought.