System Function Test
NOTE:
Replace ECU only if a thorough system check reveals no other fault. If ECU is replaced without repairing system faults, new ECU may be destroyed.
- Turn ignition off. Disconnect ECU connector. Turn cruise control switch to ON position. Connect test light between ECU connector terminals No. 1-10 and ground. See Fig 1 . If test light does not light at any time, go to next step. If test light glows, a poor connection or short circuit is present.
- Turn ignition on. Connect test light between ECU connector terminal No. 1 and ground. If test light glows, go to next step. If test light does not glow, fuse No. 12 may be blown, a circuit may be open, or cruise control switch may be faulty.
- Connect test light between ECU connector terminals No. 1 and 8. If test light glows, go to next step. If test light does not glow, a ground circuit is open.
- Connect test light between ECU connector terminals No. 1 and 3. If test light glows when pedals are up, go to next step. If test light does not glow, vacuum valve may be incorrectly adjusted, an open circuit may be present between terminal No. 3 and ground, or wire may not be connected to negative side of brakelight switch.
- Depress pedals. If test light goes out, go to next step. If test light does not go out, wires may be incorrectly connected at brakelight switch, or a short circuit may be present in wiring.
- Connect test light between ECU connector terminal No. 2 and ground. Press SET SPEED button. If test light glows, go to next step. If test light does not glow, cruise control switch may be inoperative or an open circuit may be present in wiring. Refer to CRUISE CONTROL SWITCH TEST .
- Connect test light between ECU connector terminal No. 6 and ground. Set cruise control switch to RESUME position. If test light glows, go to next step. If test light does not glow, cruise control switch may be inoperative or an open circuit may be present in wiring. See CRUISE CONTROL SWITCH TEST .
- Connect a jumper wire between ECU connector terminals No. 1 and 10 and another jumper wire between ECU connector terminals No. 8 and 7. If engine vacuum pump produces a clicking noise, go to next step. If pump does not click, an open circuit is present in wiring.
- Connect an additional jumper wire between ECU connector terminals No. 8 and 4. Vacuum pump should start and vacuum servo should move accelerator pedal all the way down. Remove wire from terminal No. 4. If vacuum pump stops, system is okay. If pump does not start, an open circuit is present in wiring. Release accelerator pedal by disconnecting wire from terminal No. 7.