E91 Part 2 of 2

Diagnostic Chart.:

Wiring Diagram.:

DESCRIPTION:

This diagnostic test monitors the binary code generated by the four input switches of the PRNDL switch.

If a code generated by these switches is not recognized by the PCM, the code will set.

TEST CONDITIONS:

Continuous.

FAILURE CONDITIONS:

1. An open or short to ground in one or more switches or circuits that would generate an invalid binary code.
2. An engine start with a code recognized by the PCM as one for a forward or reverse gear.

ACTION TAKEN:

1. Code is set.
2. BCM turns on SERVICE ENGINE SOON lamp.

NOTE ON INTERMITTENTS:

The PCM code snapshot provides valuable information in diagnosing an intermittent code E91. If all digits of L.2.2 and L.2.3 are 1, then check for an intermittent loss of ground to the PRNDL switch. If an intermittent code E91 occurs when the transmission shift lever is moved, the code is most likely caused by a misadjustment of the shift linkage or PRNDL switch, causing the PRNDL switch to end up in the range between gears.

On the other hand, if the code occurs and the service engine soon message comes on while driving or when the driver is not moving the gear selector lever, record L.2.2 and L.2.3 and compare the values to the chart. For example, if the driver was driving in OD when the message came on and L.2.2 reads 10 and L.2.3 reads 11, check for an intermittent open in CKT 773. Manipulate related wiring and connectors while observing parameters P.2.2 and P.2.3 (or scan tool display). If an intermittent is induced, the digit corresponding to that circuit will change. If wiring and connectors check out OK, substitute a known good PRNDL switch and recheck.