A.Loss of Power or Ground to the ECM

Check:

1. Loose battery cable (all models).

Additional symptoms may include radio clock reset, headlamp dimming or slow cranking. Check for proper tightness of both positive and negative connections, and check for leakage at battery terminal or terminal corrosion.

2. Loose junction block connections; the point at which the fusible links are connected can create arcing when loaded or when opened intermittently on bumps, acceleration, and deceleration.
a. The 6.0L (368) engine, the 1981 4.1L V-6, and 1982-1985 four-cylinder Cimarron all use starter solenoid battery post as a junction block. Check the fusible links for corrosion and proper termination, and check the solenoid stud for tightness.

b. Check the jump start junction block underhood on 1982 V-6 and 1982-1985 HT4100 equipped Cadillacs. Check for tightness and check the fusible links and cables for corrosion and proper termination.

3. Loose engine grounds. False codes 23 (DFI), 25 (1982 DFI), 42 (CCC and EFI), 52 (DFI), 13 (all models) can be set.

a. Check both sets of engine grounds at engine right front under the generator. Check the braided ground strap on the ground stud toward the front of the car. (1980-81 V-8 and 1981-82 V-6).

b. Check engine grounds at cruise power unit (1980-1981 V-8 and 1981-1982 V-6).

c. Check engine grounds on engine right side. One ground stud is at the front of the engine under the rocker cover, one ground stud is on the AIR valve bracket. (1982-85 Longitudinal V-8)

d. Check for loose or improperly connected engine and body ground attached to the engine cradle near the starter and grounds attached to generator. (1985 FWD "C").

e. Cimarron; check grounds on engine above front side of transmission, on the rear of engine below distributor, and on cowl left side at tach filter.

f. All models - ground to fender from battery negative cable.

4. Check ECM edgeboard or header connectors for proper termination and verify all connectors are securely latched.

a. Check for steady battery voltage on ECM power circuits with a digital voltmeter, engine running.

b. Check for voltage on ECM grounds, engine running. Measure voltage with voltmeter; place one probe on the ground terminal of the ECM and one at the main engine ground. The voltage should be 0 volts +/- .10 volts. As a rule of thumb, voltages out of this range indicate poor connection to main engine ground, see checks in Item A, Step 3 above. Examine the ECM ground circuits at the bulkhead connector, look for pins bent over or backing out of the connector.