M2 CUMMINS ALLISON NO CRANK

ADAM KEEP 4 posts since Jun 6, 2019
M2 CUMMINS ALLISON NO CRANK Dec 29, 2020 6:39 PM
SERIAL # JB3069
DOING A WRITE UP FOR THIS ONE AS THERE WAS NO REAL HELP OUT THERE FOR A NO CRANK
ON THIS M2 CUMMINS ALLISON SETUP.
SO THE SHORT STORY, CUSTOMER STATER TRUCK INTERMITTENTLY HAS NO CRANK. TECH WAS
ABLE TO SUCCESSFULLY CRANK AND CONNECTED DL TO VIEW STATUS. SAW CRANK SIGNALS
FROM IGNITION INPUTS TO BHM AND OUTPUT FROM BHM B4.B WITH NO LOAD SHOWING IN
OUTPUT.

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M2 CUMMINS ALLISON NO CRANK

AFTER TESTING ALL OUTPUT AT B4.B AND FOUND NO VOLTGE OUTPUT FROM BHM AND TESTING
STARTER RELAY AT B4.B AND WAS ABLE TO CRANK AND RUN BY APPLYING 12VDC TO B4.B WIRE,
BHM WAS REPLACED. THIS DID NOT CORRECT THE PROBLEM. SO... VIEWING THIS TAB IN DL,

NOTICE THE "RPM" DISABLE STATUS IN "CRANK ENABLE INDICATORS". THIS IS THE POINT WHICH
THER IS NO CLEAR INFORMATION AVAILABLE AS TO WHAT THIS STATUS COMES FROM. CAC

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M2 CUMMINS ALLISON NO CRANK

STATED THAT "IT IS NOT NESSESARILY A RPM SIGNAL". SO FURTHER DIGGING INTO WONDERFUL
E-Z WIRING, TECH WAS ABLE TO FIND A NEUTRAL SIGNAL CIRCUIT AT TCM 80 WAY CONNECTOR
PIN 41. DRAWING G66-02082-002 THIS SIGNAL CONTROLS R7 RELAY COIL WHICH THEN SENDS A
GROUND THROUGH R7 RELAY CONTACTS TO CHM CONNECTOR 5 PIN A WHICH THEN ALLOWS
THE "RPM" CRANK ENABLE TO BE ALLOWED. IN HIS CASE THERE WAS A DAMAGED WIRE,
INTERMITTENTLY OPEN, IN THIS CIRCUIT 497F BETWEEN THE R7 RELAY AND CHM. AFTER RUNNING
AN OVERLAY FROM R7 RELAY TO CHM C5 A, THE TRUCK CRANKS EVERYTIME.
I HOPE THIS HELPS SOMEONE ELSE AS THE SCHEMATICS AND TEMPLATES CAN BE MISLEADING. I
HAVE ATTACHED ALL THE SNAP SHOTS AS WELL.
• G66-02082________________-_.001.pdf 33.4 KB Preview
• ignition switch status.jpg 119.5 KB
• crank enable indicators.jpg 181.5 KB
• b4_b crank no load.jpg 160.5 KB
Tags: neutral start, m2 no crank, crank enable, r7 relay

Jesse Gutierrez 480 posts since Mar 5, 2017
Re: M2 CUMMINS ALLISON NO CRANK Jan 3, 2021 11:52 PM
Where was the damage found , was it in the harness which comes off the bhm, down near the rear of the
engine to the trans?? I had a similar issue were my harness was rubbing on the formed metal air line by
chance??

ADAM KEEP 4 posts since Jun 6, 2019
Re: M2 CUMMINS ALLISON NO CRANK Jan 4, 2021 3:18 PM
SO THE TECH DIDN'T LOCATE THE DAMAGED SECTION, JUST RAN AN OVERLAY DUE TO THE
AMOUNT OF TIME WRAPPED UP IN THIS JOB. OVERLAYS ARE NICE UNTIL THE AREA CAUSING THE
DAMAGE CONTINUES AND OTHER CIRCUITS ARE AFFECTED.!.!.

Jesse Gutierrez 480 posts since Mar 5, 2017
Re: M2 CUMMINS ALLISON NO CRANK Jan 4, 2021 4:23 PM
very true about overlays, which is kinda why I was asking to see if it was a common spot where damage
occurs ? Something I like to do to pinpoint damage wiring is I will connected my meter to grd , and the other
lead to the circuit I think is damaged and wiggled my harness until I reach the exact point or near it where my
meter starts to go wild once I move that section of harness .. then cut that section of loom open and determine
what exactly needs to be repaired etc...….but great job on the find!!!!!

Chris Vanboom 185 posts since Nov 21, 2014
Re: M2 CUMMINS ALLISON NO CRANK Jan 6, 2021 4:10 PM

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M2 CUMMINS ALLISON NO CRANK

I have come across this issue before, the DDDL template is terrible at clarifying. This truck is spec'd with a
remote start option, and I have battled with this issue on other trucks with remote start/stop. If you look at the
parameters in CHEC there is some clarification in parameter 26-01007-067 which shows the hardwire "neutral
safety" circuit. On trucks equipped with a manual transmission the mechanical switch is on the transmission.
The circuit is controlled by the hood tilt switch in this case.

Anthony Kasper 5 posts since Aug 26, 2020
Re: M2 CUMMINS ALLISON NO CRANK Jan 15, 2021 8:51 PM
Did you verify on Allison DOC the TCM is reading Neural ?

ADAM KEEP 4 posts since Jun 6, 2019
Re: M2 CUMMINS ALLISON NO CRANK Jan 28, 2021 8:06 PM

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M2 CUMMINS ALLISON NO CRANK

Yes all that was checked. My point in this write-up was the template does not lead you to think of a "neutral
safety" status due to the "rpm" button. so no original thought was put toward any neutral inputs.

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