PCM Relay

[Roscoe P]

Can anyone give me the exact location of the PCM relay ? I want to remove the relay ,to reset the PCM without losing the data for the trans
etc.I put in a performance chip sometime back and it's not made me happy. I want to reset to original specs. I lost @ 9 mpg for a road trip.
I have removed the chip but the tune is still in there . Mileage around town has suffered as well . Think its better to go back to original spec
and see what they may do with the trans.
Thanks
Roscoe P.

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[airline tech]

If you have tuned it, then that is a software change to the PCM, if you remove power.
Via Battery Disconnect, Fuse Pull or Relay pull it's still going to hold the Tune.
But if you look at the (Engine Bay) Fuse box:
Fuse 7 = PCM Power and just to the (Left) of Fuse 7 is the PCM Power Relay

I think you have to flash it back to stock; it would be helpful to know what Tune was installed for others to provide some input that have tuned their Ranger.

 

[Roscoe P]

If you have tuned it, then that is a software change to the PCM, if you remove power.
Via Battery Disconnect, Fuse Pull or Relay pull it's still going to hold the Tune.
But if you look at the (Engine Bay) Fuse box:
Fuse 7 = PCM Power and just to the (Left) of Fuse 7 is the PCM Power Relay

I think you have to flash it back to stock; it would be helpful to know what Tune was installed for others to provide some input that have tuned their Ranger.

I stalled a Thorten Performance Chip . It was a plug and play. Supposedly it was removed after you removed the chip but don't believed that's how it actually worked .My MPG has suffered tremendously. The trans shifts worse now. Ready to go back to what I had. Don't want to do a disconnect because of the trans data.

 

[airline tech]

I think all that chip does is alter the Idle Air and Fuel Trims, so the PCM can adapt a learning table based on that chip.

So, with it removed after a few hundred miles or so, it should adapt back to factory learning tables on its own.

However, you can force a reset by (Resetting the KAM - Keep Alive Memory)
This process however is not clear (if this also resets the Transmission Learning)

It's easier to do with a scan tool, I think Forscan has it as well.
Just click on the RESET KAM tab.

Resetting The Keep Alive Memory (KAM)
Description
Resetting the KAM returns the PCM memory to its default setting. Adaptive learning contents such as adaptive airflow, idle speed, refueling event, and fuel trim are included. Clearing the continuous diagnostic trouble codes (DTCs) and resetting the emission monitors information in the PCM, is part of a KAM reset. Refer to Clear The Continuous Diagnostic Trouble Codes (DTCs) And Reset The Emission Monitors Information In The Powertrain Control Module (PCM) in this section.

After the KAM has been reset, the vehicle may exhibit certain driveability concerns. It is necessary to allow the engine to idle at normal operating temperature with the A/C off for 2 minutes. Then drive the vehicle to allow the PCM to learn the values for optimum driveability and performance.

This function may not be supported by all scan tools. Refer to the scan tool manufacturer's instruction manual.

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