Service Procedures

1. Retail Customer - Inspection Requirements

When a customer reports the following conditions, check all electrical systems with the MS 1700 tester.

^ erratic acceleration during the first two to five minutes of initial warm-up

^ rough idle at normal operating temperature

^ uneven acceleration at normal operating temperature

Follow the Electronic Control Unit Preliminary Inspection/Diagnostic Checklist (P/N 8980 010 563). If there are faults indicated, repair them as necessary. If there are no faults indicated, replace the ECU as described under ECU Replacement below.

FIGURE 1:

FIGURE 2:

2. Vehicles Sold From Dealer Stock - Inspection Requirements

All automatic transmission equipped Medallion models ordered by dealers on or after July 27, 1987 have been equipped with the latest generation ECU. This can be confirmed by the presence of a daub of paint on the visible end of the clamshell that houses the ECU, as seen in A - Figure 1 and/or by the presence of the homolagation number HOM 7700 742 979 on the ECU below the part number as seen in the highlighted section of B - Figure 2.