Truck won’t start and transmission pad not lighting up

[BrooklynnMasonry]

Hey all, this is my first time posting to the forum. With that said my M1078 just arrived on the truck, just to find out it won’t start. The driver drove it on the truck and was letting it idle to charge the batteries and it had a check trans light on the dash. It’s sorta fuzzy from there he said it died and wouldn’t start. I figured probably the batteries were bad and maybe not enough power to the circuits so I bought 4 group 31s the day before it was delivered. Anyway we ended up installing them to try and get it started with no luck. I was thinking back to the driver mentioning a trans light on and the truck dying. I then noticed the Allison keypad not lighting up saying it’s in neutral. After what seemed like hours one of my neighbors came over that’s a diesel mechanic for a near by fire department and pulled some relays out and was able to apply power to the neutral start relay. Bam like a bolt of lighting it fired right up! Still no selector visible on the Allison key pad.... no forward or reverse. My neighbor pulled it off the trailer with his backhoe now that we had breaks now it sits hoping someone here has had the same problem as I! Can you guys guide me in the right direction!! Thanks Bryan.

 

[Ronmar]

Trans power comes from CB79, you need it to power the trans which in turn gives you a neutral start relay to start the truck. Could be low power and it pulled more current than cb79 could handle...

 

[BrooklynnMasonry]

Trans power comes from CB79, you need it to power the trans which in turn gives you a neutral start relay to start the truck. Could be low power and it pulled more current than cb79 could handle...

Great! I’ll check it as soon as it’s light outside!

 

[BrooklynnMasonry]

Great! I’ll check it as soon as it’s light outside!

It’s an 03 with a 3126 cat if that makes a difference or helps!

 

[Suprman]

Sounds like a bad trans tcm its under the dash behind the passenger side kick panel. I have replacements. You can also check the circuit board power panel. Some used low lead solder and can develop bad solder joints.

 

[BrooklynnMasonry]

Sounds like a bad trans tcm its under the dash behind the passenger side kick panel. I have replacements. You can also check the circuit board power panel. Some used low lead solder and can develop bad solder joints.

Is there a way of testing it?

 

[Suprman]

Where are you located?

 

[BrooklynnMasonry]

Where are you located?

Seattle, Wa.

 

[Suprman]

You can send to me to test it if you want. Wtec3 tcms are easy to kill when jump starting the truck unfortunately

 

[BrooklynnMasonry]

You can send to me to test it if you want. Wtec3 tcms are easy to kill when jump starting the truck unfortunately

Where are you located?

 

[BrooklynnMasonry]

Where are you located?

And how much is a new one?

 

[Suprman]

CT. A used replacement is 550 shipped

 

[Ronmar]

For the A1 CB79 is ignition(switched) power and CB43 is battery power to the Trans controller...

 

[Third From Texas]

What year truck?

A1's have a battery disconnect that will kill the works.

 

[BrooklynnMasonry]

CT. A used replacement is 550 shipped

Ok, I will double check when I get home to

What year truck?

A1's have a battery disconnect that will kill the works.

Its an 03, I have found 2 battery switches one under a box to the right of the battery box and one under the steering wheel. When I lift the cab I found 3 switches on the passenger side in between the wheel and the motor any idea what those could be?

 

[Ronmar]

The ones under the cab on passenger side are remote start switches...

 

[BrooklynnMasonry]

Oh ok!

 

[abfisher1798]

You can send to me to test it if you want. Wtec3 tcms are easy to kill when jump starting the truck unfortunately

I may need mine tested. What about the PDP board?

 

[BrooklynnMasonry]

I may need mine tested. What about the PDP board?

I’ve started taking it apart last night hopefully tonight I’ll be able to remove it.. what’s the PDP?

 

[Suprman]

The pdp is the circuit board breaker relay panel on 3126 trucks. Feel it see if sockets are loose in the board. Visually inspect. A bad board usually causes odd intermittent issues. The wtec3 tcm is a common failure. Keypads go bad too water drips down onto them over time and gets in.