Cruise Control

Fig. 26 DEFI wiring circuit (Part 1 of 4):

Fig. 26 DEFI wiring circuit (Part 2 of 4):

Fig. 26 DEFI wiring circuit (Part 3 of 4):

Fig. 26 DEFI wiring circuit (Part 4 of 4):

Code 63 indicates that the cruise control was engaged at a certain set speed and the vehicle speed was 20 mph above or below this set speed. Code 63 may be the result of driver error or system malfunction. To diagnose system, proceed as follows:
1. Start engine, turn ignition off and, within 2 seconds, turn ignition back on.
2. Turn on cruise enable switch.
3. Enter diagnostics and perform output cycling test as described previously.
4. Check cruise control vacuum and power valves to determine if they cycle on and off.
5. If vacuum and power valves operate satisfactorily, check for binding valve linkage, vacuum leaks or obstructions. If vacuum system is operating satisfactorily, problem is not in DEFI system.
6. If vacuum valve does not cycle, proceed as follows:
a. Disconnect vacuum valve electrical connector and connect a test lamp between connector pins. Perform output cycling test as described above. If test lamp does not light, proceed to step 6b. If test lamp lights steady, proceed to step 6c. If test lamp cycles on for three seconds, then off for three seconds, replace vacuum valve solenoid.
b. Check circuits 919 and 403, Fig. 26, for an open. If circuits are satisfactory, check cruise control vacuum valve for a short. Disconnect electrical connector and measure resistance across the valve in both directions. If both readings are less than 20 ohms, the diode or solenoid in the valve is shorted, causing damage to the ECM, which must then be replaced. If either reading is greater than 20 ohms, the ECM or ECM connector is at fault.
c. Check circuit 403 for a short to ground. If circuit is satisfactory, the ECM or ECM connector is at fault.
7. If power valve does not cycle, proceed as follows:
a. Disconnect power valve electrical connector and connect a test lamp between connector pins. Perform output cycling tests as described above. If test lamp does not light, proceed to step 7b. If test lamp flashes continuously, replace power valve solenoid.
b. Check circuits 402 and 151 for an open and repair as necessary. Check circuit 402 for short to ground. If circuit is shorted, repair and check ECM for damage. If circuit is satisfactory, disconnect cruise power valve electrical connector and measure resistance across valve in both directions. If both readings are less than 20 ohms, replace power valve and ECM. If either reading is greater than 20 ohms, the ECM or ECM connector is defective.