My 2001 Cummins 6 speed cruise control has went  erratic . Could someone tell me which  it is the ECM for the PCM that controls the cruise control 

My truck is a 2002 with a manual six speed transmission.  I am not sure if your '01 truck will be the same.  The wiring diagram for my truck shows that the ECM supplies the "speed control switch signal" and the PCM handles "sensor ground" and "speed control supply".

 

I know that some of the circuit has to pass through the clutch switch and brake switch, as well.  I would check these two areas first.  The only problem I ever had with my cruise control was a broken power supply wire in a panel just below the steering wheel which was an easy fix. The broken wire was caused by lots of use of the tilt steering wheel.   In my case I had code "0577 - cruise control switch voltage high" set.    

 

Do you have any codes set?

 

Hope this helps.

 

- John

Thanks for the input I will check down there because come to think of it now that you mention the circuit runs through the clutch and brake is well my brake controller has also been goofy lately  and  it's pigtail runs down under the dash in plugs in under there it could be I have some wires that have either become pinched or chafed and shorted causing both problems didn't put the two together until now also I have not checked for codes yet

Brake light and headlight switches could be burnt up causing issues, worth checking them out.

Edited October 23, 20177 yr by Dieselfuture

Sorry to hijack. Does anybody know if an ECM flash could convert a 2001 vacuum cruise to a DBW electronic cruise?