I'm having a similar issue mentioned in the original post. When first turn on my switch on, the WAIT light will stay on for approximately 10 to 15 seconds and then go out; normal. After the Wait light goes out, I can see the volt meter cycling. When I put a meter on it, it was going from 24v to 23v. I can also clearly my dash e-brake light (red) dimming as it cycles. The engine will start without an issue. After starting, the voltage meter clearly cycles. When I put a meter on the batteries, the voltage goes from 28v to +/- 25v. This continues for few minutes and then stops. Voltage to the batteries stays rock solid at 28.1v. 86humv said this was the control box cycling. Any idea why? Is there a sensor on the engine that is providing feedback to the box that may be defective? I did just complete rebuilding the alternator (new bearings, seals, etc.). I don't recall if this was happening before rebuilding the alternator. With the alternator working perfectly, I can't imagine it would be the issue.
Any help or suggestions would be appreciated.
Beat a dead horse thread
No horses working or retired were harmed.
NO No no. The voltage drop "window wiper" action of the voltmeter is an indication there is glow plug action.
Added>>> it is the "after glow" cycling that designers built into the box for a sure and cleaner start on off on off on off on off. IMO more to go wrong.
A full set (
of good plugs can draw 50 to 150 Amps depending on battery voltage and other variables. That's a lot of electrons making heat. Just indication the p u l l on the battery voltage.
Maybe all are working BUT good to test each first before cashing out. Check / test them all individually to be ready for winter.
Most important is the cycling shuts off after a couple minutes. If EVER the voltmeter does not recover from the back and forth... and stays LOW ... SHUT it off. That's a sign the "box" has not released the glow plug voltage. (could be alternator too. Just have to learn how your HumV behaves. lots of personality)
NINTY seconds of staying low... there's is GOOD chance you burned thru a $100 bill for new plugs. You will know when it started and ran fine to the parants for Thanksgiving dinner. Stayed for the home made pie
and it would not start when time to go home. (one of a couple likely headaches)
That little voltmeter can tell a lot of stories to whats's going on under the hood. At night with the lights on, flash back to the 70's at a disco dance party. LOL
Always nice to have some spare HumV plugs with the bullet tops, right in the glove box.
Buy if you want. IMO I think you're OK. The test is the proof. A low LOW resistance 1.5 - 5 ohms +/- Above 5 ohms questionable & toss it.
Check each and save some bucks, CAMO
