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TSB 18-36-98

Start And Stall, Idle Undershoot - Lost Idle Air Control (IAC) Steps

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Date: Dec 18, 1998

Models: 1999 BR/BE Ram with gasoline engines built prior to Dec 18, 1998 (MDH 1218XX)

1999 (AB) Ram Van
1999 (AN) Dakota
1999 (BR/BE) Ram Truck
1999 (DN) Durango
1999 (TJ) Wrangler
1999 (WJ) Grand Cherokee
1999 (XJ) Cherokee

Some vehicles may exhibit idle undershoot or die out during engine starting and may be caused by IAC lost steps.  This condition is more likely to occur during cold weather, low battery voltage, cold engine start, and quick ignition key "on-off" operation.

Using the Mopar Diagnostic System (MDS/MDS2)  or the Diagnostic Scan Tool (DRB III), verify that all engine/transmission systems are functioning as designed. If other DTC's are present, repair as necessary before proceeding with this bulletin.  If no other DTC's are present, perform the repair procedure.

NOTE:  Whenever a PCM is replaced due to failure, the software of the replacement controller should be verified for the latest revision level. Use the flash procedure to updated replaced controllers as necessary.

This Procedure involves selectively erasing and reprogramming the PCM with new software (99cal14 calibration change).

NOTE: The Mopar Diagnostic System is required to perform the ECM flash. The system must be operating with release 21 or higher AND TIL CD RELEASE 1175 or higher must be installed.
Type or print necessary info on the "Authorized Software Update" label (Fig 1) and attach it to the ECM. Cover the label with clear tape.
Type or print the following information on the Authorized Modification Label and attach the label near the VECI label (Fig 2).

Thanks to Bob Bergevin for providing this TSB information

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This page was edited on: May 3, 2004