GM Repair Questions? Ask a Mechanic for Answers ASAP
Hello & Welcome to JA,
The only response we have recieved to date is Hello and Welcome to JA.
What additional information do you need?
What code are you getting ?
Does this vehicle have a PTO ?
We have it hooked up to a Genesis and are getting engine readings but no trouble codes.
Yes there is a PTO it operates the dump bed.
Ok,check the data parameter for the PTO. If it shows that the PTO is active ,the computer will trim the engine rpm to a max lower rpm.
Here is a GM bulliten on PTO switch
PIP3187A: Engine Has Lower Power Check PTO Switch - keywords 6.6 6.6L 8.1 8.1L allison automatic diesel fuel L18 lack LB7 LBZ LLY LMM MAF no pressure RPM sluggishness sponginess speed - (Jun 9, 2009)
This PI was superseded to update model years. Please discard PIP3187.
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
A customer may have a concern of low power. The dealer may notice that the engine will not go over 2000-2300 RPM.
A low power concern can be induced if the Power Take Off (PTO) switch is on.
If a low power concern has been duplicated, complete the current SI diagnostics for any trouble code or symptom found. During diagnosis be sure to check the PTO switch. When the PTO is enabled, it may limit the engine speed between 2,000 and 2,300 RPM (RPM that is reached may be dependent on actual PTO settings).
If the PTO switch is on, lower than expected readings on the FRP Regulator Fuel Flow Command, Turbocharger Boost Pressure, and Mass Air Flow readings may be noticed.
It may also cause changes in transmission operation such as long or delayed upshifts.
Evaluate low power after PTO has been disabled.
Thanks for your time it turned out to be that the traction control button was on.