volt meter jumping

[rookie]

Guys my voltmeter on my 94 m998a1 jumps when im driving at idle it reads fine but when i accelerate it bounces like crazy what could that be?

 

[papakb]

First question, is it the original alternator and how many miles are on the truck? Sounds like the brushes in the regulator are worn out and not making good contact at RPM. The brush block is available from Southern Automotive as a separate part here:

http://www.southernautomotive.com/catalog/product_info.php/cPath/22/products_id/29

This breakdown is applicable to the 60 amp alternators.

Kurt

 

[rookie]

Its a 94 m998a1 with a 2012 nehooff 200 amp dual voltage the truck has 34k

 

[Retiredwarhorses]

Check the gauge grounds...as well as other wiring. Bring the idle to 2k rpm and check output...see if it's fluctuation on output....if it is, the regulator is bad.

 

[rookie]

I will check the grounds on the gauge. How do u check for fluctuation on output? Also will this hurt anything

 

[papakb]

If you haven't installed the supplemental ground harness I'd strongly suggest you find or make one and put it in your truck. It will solve problems like this and eliminate future problems. There are directions on how to make them and install them on most HMMWV sites. Part of installing the harness is going through the ground system and making sure everything is clean and tight. One of the worst grounds is also one of the most important and that's the one through the firewall behind the heater controls. They tend to corrode fairly easily and this is where your gauge panel ties into the ground system. On my truck I installed a long 1/4-20 setscrew with nuts and star washers on both sides of the firewall and then tied everything else into that. Another hint is to use plenty of electricians anti-oxidation grease on the connections to eliminate water wicking and corrosion.

Kurt
KG6KMJ

 

[rookie]

Thanks a lot kurt i will try all that and keep u guys posted to see what fixes it thanks

 

[rookie]

Well guys i just wanted to inform u that i installed a grounding kit and went thru all the grounds some were a little loose but the problem got fixed thanks for all the input thats why i love this forum very helpful guys thanks

 

[papakb]

It's always nice to get a little feedback when your helping people out. Too often we forget to do it.

Kurt

 

[rookie]

Yes indeed.