M923A2 Won't start... All the lights work though!

[porkysplace]

Fully charged batteries should read closer to 27v.

 

[crolfe1984]

If it happens again and the gauges don't work, turn the fan on to high and see if it works. The high setting is 24v and runs through the PCB and the low setting is 12v and doesn't run through the PCB. If it doesn't work on high but does work on low and your gauges are not working then I'd be looking at the PCB.

VERY interesting... Indeed my lower blower works, but high does not. I have an undiagnosed ABS fault so the light is on (which is my next project to tackle). As far as the ABS is concerned it does not even self check so its either a bad ECU or its not getting power at all. I can tell you already it's not a loose connection.

 

[Swamp Donkey]

My ABS wouldn't self check either. I think it detects low voltage and just throws the light.

My PCB would appear to work fine sometimes, as in letting you crank the truck, but apparently would stop charging sometimes while the truck was running. This led to the batteries eventually draining. One morning it didn't have enough battery power to crank the truck. I charged the batteries, fired it up and the ABS light went away...until the batteries eventually ran down again. Replacing the PCB fixed all my problems...the fan, the ABS, the charging and the starting.

Porkysplace is right...a little over 24v is low.

 

[crolfe1984]

I may just bite the bullet and pick up a new PCB. Replacing it might make a few of my electrical issues disappear. I'd rather do that then replace four 6TL batteries.

 

[Tornadogt]

I added a post to this thread:
http://www.steelsoldiers.com/showthread.php?113634-Ever-see-inside-the-Protective-Control-Box/page3

I carry the Two pieces of wire in the tool kit to jump/bypass the PCB box if it ever leaves me stranded. Just a small piece of mind. and great on new truck recoveries.

 

[crolfe1984]

That's brilliant. When I make up my road-ready tool kit I'll be sure to have a section of 4-8 copper wire.

Out of curiosity, what tool did you use to get that giant castle nut off? Haven't removed mine yet, but I'm guessing a pair of channellocks will do it.

 

[Tornadogt]

That's brilliant. When I make up my road-ready tool kit I'll be sure to have a section of 4-8 copper wire.

Out of curiosity, what tool did you use to get that giant castle nut off? Haven't removed mine yet, but I'm guessing a pair of channellocks will do it.

I used Channellocks

 

[paintman]

my issue with my m923a2 1990 model is i go forge deep water with mine, usually not into the cab but over front fenders... never gave me an issue till today... went to start, turned on battery switch, check... turn on starter switch, check... buzzers and gages show power.... hit starter switch... motor turns but doesnt fire....sounds strong, noticed when i release starter switch, she keeps turning over till i switch both switches off....never had this issue before. i also went from having c.t.i.s. with a single light to all lights flashing at same time shortly after she starts up and builds air pressure....any suggestions

 

[paintman]

i got it running by tapping the pcs with a wrench so if it happens again, how much and were do i get one.... still issue with the a.t.i.s. all lights are flashing at once and abs light has been on since i got the 5 ton

 

[juanprado]

i got it running by tapping the pcs with a wrench so if it happens again, how much and were do i get one.... still issue with the a.t.i.s. all lights are flashing at once and abs light has been on since i got the 5 ton

My recommendation as they are an oe source for the Protective control box is Southern Automotive as they are reasonable and will sell direct. I think you will find a new one there for close what others sell used ones.
http://southernautomotive.com/catalog/index.php

For the abs, there are many threads on it but there is 2 automotive mini ato fuses in the harness. Check em out. If fuses good, then you need to run the abs codes to determine what critter is the problem. Again many good threads in the 5 ton forum.

I have zero experience with ctis but many threads on that here. Search is your friend

 

[crolfe1984]

As an update I have 100% confirmed that my PCB is on the fritz. Every other time now requires a thorough thumping to get it to "click over" so the truck can be started. Once the weather warms up I'll get one ordered and replace it. Then I'll tackle the ABS fault. I've got to say though that despite this one issue the M923A2 has been an awesome truck to have this winter.

 

[Mquirin]

Where is the pcb located on the m35a3? I put in new batteries, but have no headlights and only a click at the firewall. Could this be a bad power switch?

 

[Ajax MD]

Where is the pcb located on the m35a3? I put in new batteries, but have no headlights and only a click at the firewall. Could this be a bad power switch?

I believe it's on the firewall in front of the driver, under the hood.

 

[Mquirin]

I believe it's on the firewall in front of the driver, under the hood.

Mine doesn't appear to have one, or it must be in a location I can't locate.

 

[Ajax MD]

Oh shoot, you're in the 5 ton forum. Ask the question in the deuce and a half forum. Someone will know.

I've driven the M35A3... when they were new!