Abs light on, new to me M925a2

[101coolcars]

I recently won a m925a2 and I'm figuring out the recovery, I noticed in one of the pictures from gp the abs light looks to be on, do you think this is an indication of a fault? Or normal during startup? What would the consensus be in terms of a driving recovery with a active abs light in?

thanks in advance
terry

 

[sandcobra164]

When the ABS light stays on, that indicates a fault with the ABS system. The brakes should still work fine but will not have protection from locking up. I've driven a few with that light on and never had any trouble. The Military installed ABS on these trucks to solve a peculiar problem. Driver's would attempt to panic brake and lock up the drivetrain. Once this happened, the torque converter wouldn't unlock in time to prevent stalling the engine. Once stalled, the power steering system is not in play and the M939 series suffered quite a few rollovers. If you drive with caution as you should anytime you operate one of these, you should be fine.

 

[Swamp Donkey]

To quote you from another thread...

yes i did buy one, a m925a2 out of kansas last wenesday. now i have to figure out the recovery. they say its a runner with a jump.

The ABS system is very voltage sensitive, to include low voltage, and will throw the light if not between the limits. Voltage is obviously low if they have to jump it off. I'd start with getting the batteries back in shape before moving forward with troubleshooting. Congrats on the truck!

 

[Ue413]

I've got one with the light constantly on ang good batteries. Can air leaks be a root cause?

 

[74M35A2]

No. Check the 2 in-line blade fuses at the steering column in the cab. If the large one is blown, and blows again as soon as you flip the battery switch on, then the ABS module is fried, likely from an over-voltage occurrence if the truck switches are shut down in the opposite order of what they are supposed to be.

 

[The HUlk]

When the ABS light stays on, that indicates a fault with the ABS system. The brakes should still work fine but will not have protection from locking up. I've driven a few with that light on and never had any trouble. The Military installed ABS on these trucks to solve a peculiar problem. Driver's would attempt to panic brake and lock up the drivetrain. Once this happened, the torque converter wouldn't unlock in time to prevent stalling the engine. Once stalled, the power steering system is not in play and the M939 series suffered quite a few rollovers. If you drive with caution as you should anytime you operate one of these, you should be fine.

Can't verify accuracy but I read the military put a low speed limit (41mph?) on the early M939s until they were upgraded with the ABS system. Bear in mind over braking is not something you want to do especially with no load meaning less traction.

 

[The HUlk]

I've got one with the light constantly on ang good batteries. Can air leaks be a root cause?

I've got one with the light constantly on ang good batteries. Can air leaks be a root cause?

I would guess a signal problem from the wheel sensor(s) may cause a fault. Manuals are here...

http://www.steelsoldiers.com/showthread.php?121487-TMs-for-M939-Series-Trucks

 

[lindsey97]

Take 2 new batteries with you to Ft. Riley. 9/16" wrench, 1/2" wrench, pair of channellocks, gloves, and a can of ether. Use ether sparingly.

Couple of cans of diesel won't hurt either as the truck may well be empty. Also, an air hose with tire chuck, and glad hand on one end. Some shell rotella motor oil, and a couple gallons on antifreeze to top her off.

 

[101coolcars]

Thanks, I've got a pretty big recovery list going. My "plan" is to drive my M1009 to Kansas and bring my new medium towbar I just got from m35cat here on the classifieds and drive the 5 ton towing the cucv behind. No current spare for the 5 ton is my current issue.

 

[lindsey97]

Spare tires will be available when you pick up your truck. You will need cash. Or go by BFR metals in Salina, glen will fix you up with spares.