No start A1

[GreyEnvy]

Picking up M1078 A1 (15k serial, so early A1) from GSA, it had dead batteries and had to be boosted to start. The volt meter bounced from one end to the other and the transmission would only engage for a few seconds at a time.

I pulled the four dead 6TL and replaced with 2 group 31 using the usual schematic from the forums. At this point it cranked right up and the transmission seemed to be working.

I let it high idle 15 minutes while doing other things, then turned it off and now it won't start. It turns over plenty fast but makes zero effort to fire. Not even a hint.

I feel like there is some sort of start inhibit going on.

I checked all the circuit breakers, swapped a few around, swapped a few relays around (not mixing up the 12V and 24V), no change.

The yard guy said they won't run on 2 batteries because the computer senses there isn't 4 present. But I know most people here are running 2 batteries.

I can't get the TM to download on my tablet.

Ideas?

 

[Third From Texas]

Prime it? Could be fuel? Is the bulb hard?

Your yard guy is wrong.

 

[Keith Knight]

My 2003 A1 did that when the ECM / Engine control module died. I had to get a mobile cat service tech to connect to it and diagnosed it.

 

[GreyEnvy]

Prime it? Could be fuel? Is the bulb hard?

Your yard guy is wrong.

The cab lift doesn't work.

 

[simp5782]

The cab lift doesn't work.

You can reach it thru the fender skirt

 

[Ronmar]

You should get a check light from the ECU to indicate it is Powered/booting up.

they also added a power filter down by the ECU these usually get bypassed and there is probably a reason for that.

the hand pump doesn't even work?

 

[fuzzytoaster]

The yard guy said they won't run on 2 batteries because the computer senses there isn't 4 present. But I know most people here are running 2 batteries.

You can use 2 batteries yes. He doesn't know jack nor does the computer about number of batteries.

Picking up M1078 A1 (15k serial, so early A1) from GSA, it had dead batteries and had to be boosted to start. The volt meter bounced from one end to the other and the transmission would only engage for a few seconds at a time.

The TCM will do a voltage check and if too high or ohm's out of spec it will default to safe mode and not move.

I pulled the four dead 6TL and replaced with 2 group 31 using the usual schematic from the forums. At this point it cranked right up and the transmission seemed to be working.

I let it high idle 15 minutes while doing other things, then turned it off and now it won't start. It turns over plenty fast but makes zero effort to fire. Not even a hint.

I feel like there is some sort of start inhibit going on.

I checked all the circuit breakers, swapped a few around, swapped a few relays around (not mixing up the 12V and 24V), no change.

This could be a simple fix or ECM is very dead. Start simple.

1. Does it crank?
2. Do you see smoke from exhaust?
3. Does it fire on ether/starting fluid?
4. Do you have fuel prime?
5. Do you have a J1939 OBDII capable device to plug into the kick panel to communicate with the truck? If so then try to pull codes.
6. If still no fire then lift cab and remove ECM. Take it to Cat and ask them to communicate with the ECM. If they can't it's dead.

The unfortunate truth is all ECMs have batteries and some of these units blank out if the battery dies. I did a write up a few years ago with nearly the same symptoms as you have. The ECM was bad in mine and maybe it had one last go before it went on yours. Keep us posted.

 

[Suprman]

The filter inline with the power to the ecm is a common culprit. Not enough fuel pressure at the pump and the computer wont open injectors. You can plug in a standard heavy truck diagnostic reader and see if any codes or the ecm even communicates. There is a breaker for the ecm. The power panels in those trucks can suffer from lousy solder joints causing intermittent issues.

 

[GreyEnvy]

the hand pump doesn't even work?

Nope, no hand pump action.

 

[Ronmar]

Nope, no hand pump action.

There is an allen head plug on top of the hand pump and you can add oil to its reservoir directly. then both selectors need to be set to the correct positions of course…