Conditon and Cause

1. "Check Engine," "Service Now," "Service Soon" "Coolant" lamps flickering or intermittent. No codes or multiple codes. Commonly occurring with flickering "Check Engine" or "Service" lamps are the following stored codes:

A. 23 (1980-1985 DFI)
B. 25 (1982 DFI)
C. 51,52 (1982-1985 DFI)
D. 42 (1981-1984 CCC and Cimarron EFI)

2. MPG or fuel data display goes blank or is erratic, fuel used and average MPG may reset to zero. If outside air temperature is being displayed, ECC head may blank (all DEFI and DFI, 1980-1985).

3. In diagnostics, the ECC head goes blank, may exit diagnostics, display only two dots ("snake eyes"), may reset ".7.0"or ".1.8.8" (all DEFI and DFI, 1980-1985).

4. Intermittent rough running, idle surge or high idle speed, random engine quits (all DEFI and DFI, EFI, CCC, 1980-1985).

5. Intermittent cruise control disengagement accompanied by one or more of the above symptoms (all DFI 1981-1985).

CAUSE:

All of the above can be caused by ECM resets due to:

A. Loss of power or ground to ECM.
B. Large voltage variations or transients on ECM power or ground wires.
C. Large voltage variations or transients on ECM connected signal wires such as MAP, BARO, EST, or TPS.