M1079a1 start issue

[Union5]

The other day I started up my m1079a1 and the air brake alarm wouldn't go off. All the dash light were blinking. And no air pressure showed in either tank. I turned off the truck released all the air from the tanks and tried to start it again. Now the ignition switch flips Dash's lights for a second then goes dead. When you press the button all the lights go on it tries to turn over then stops and the dash goes dead. Any ideas?

 

[Suprman]

What year truck? Are your batts fully charged and battery connections clean and tight? That truck does not like low voltage. On the right side of the batt box do you have cutoff solenoids?

 

[Union5]

2007. I'll check for solenoids

 

[Suprman]

Is it a 3126 or C7? My first though would be a battery related issue. How old are the batteries? What type?

 

[Union5]

It's a 3126. Batteries are the originals from 07 I imagine truck had 98 miles on it. They are hawkers

 

[Suprman]

Hawkers are great batteries. You can get a good 8 years out of them if properly maintained. Get new ones.

 

[Union5]

Batteries are 2015 dated. I don't think it's a voltage issue. After the switch is flipped it doesn't seem like the compressor is doing anything. The ctis is blinking hwy but no activation of the compressor. The alarm for the low brake air pressure does not go off and no dash lights remain lit. The trans boots up and shows it's in neutral but when you go to start it does a half turn all the dash lights. And then nothing. Would a ctis issue cause a fail safe so it doesn't start?

 

[Davisonsite]

No the Ctis will not stop it from starting, If the Batts are good then check the starter. You know the starting system is working because it tries to start.

 

[Suprman]

Sounds like a power issue. Are you sure your batts are fully charged. Do you have the green pcb power panel or the 4 breaker boxes?

 

[Suprman]

Compressor is on the engine. No running motor no air being built.

 

[Union5]

So after the initial flip of the ignition switch and the dash lights going out. The lamp test does nothing. And no alarm for low air pressure.

 

[Johno176]

If that is the original engine it should be a C7. From 2005 on, they used the C7 electronic version of the 3126.

 

[snowtrac nome]

still sounds like a bad battery or 2 get a multi meter each battery should be over 12 volts. wouldn't hurt to take them into a store like auto zone who will test the batterys for you

 

[Suprman]

There are 3126 trucks made in 2007. Could be a bad 24v power relay. The inside of the panel has a diagram. You can swap it out for a less important relay. But I still think it's bad or weak batts. How often is it driven? 3126 should be green circuit board panel. There are power wires coming up that bolt to the board. Grounds on those are minimal at best.

 

[Union5]

We have a m998 too. So if I hook up the running m998 to the m1079a1 through the slave port it's should start normally if it's batteries right?

 

[Suprman]

Slave it up. Let it sit for a few min so the batts can get a bit of charge in them. Then turn on the power switch see how it goes.

 

[Davisonsite]

Yes it should, I would let it charge for about 10 -15 minutes . It sounds like the Batts are low on AMPS not voltage. Amps take time to build. I have had to charge trucks for over an hour when the Batts were drained way down, it takes only 15 mike of the volts to recover but a hour for the Amps to reach a point to start a truck.

 

[Union5]

Yes it should, I would let it charge for about 10 -15 minutes . It sounds like the Batts are low on AMPS not voltage. Amps take time to build. I have had to charge trucks for over an hour when the Batts were drained way down, it takes only 15 mike of the volts to recover but a hour for the Amps to reach a point to start a truck.

Ok, did not have a ton of time this morning but slaved to the m998 let it run at high idle for 10 min. M1079a1 started right up. but the ABS light stayed on. Drove the truck around a little braking seemed fine. did i just not charge the batteries up enough and still had an issue on start up?

 

[Suprman]

Hawkers need a long deep charge. No trickle charging for them. If you dont have a big heavy duty 24v charger then take them out and charge individually. Minimum 15a charge for 24 hours each. Then put them back in the truck and make sure the alternator/charging system is working.

 

[NDT]

AGM batteries that are badly discharged or sulfated will need weeks of pounding by an AGM charger. Then they will be good as new. Several threads on this.