Chart A-3 Service Engine Soon Light and No Codes

Chart A-3:

Wiring Diagram.:

DESCRIPTION:

PCM/BCM communications are carried over CKTs 491 and 526. CKT 491 carries information from the BCM requesting information from the PCM, and CKT 526 carries information from the PCM to the BCM. If data is lost over CKT 526, the BCM will not be able to display the data from the PCM and code F32 will be current.

Trouble code E47 indicates that the PCM is not receiving data from the BCM, and code F32 indicates that the BCM is not receiving data form the PCM.

The PCM MEM-CAL encodes the data from the BCM. A failure or misapplication of the MEM-CAL will cause a code E47 to set, and the same is true for the BCM. A failure or misapplication of the BCM PROM will cause a code F32.

In all cases both the MEM-CAL and PROM should be checked for proper application by checking the broadcast code on both components.

NOTES ON FAULT TREE:

1. An interruption of power or ground to either the PCM or BCM can also cause the codes to set.
2. Removal of MAXI fuse 4 interrupts power to the PCM and BCM and should cause both components to reset.
3. Code F32 is intermittent at this point.
4. If instantaneous fuel economy varies while driving, CKT 526 (PCM to BCM data) is OK, and CKT 491 should be checked for an open or short to ground.