Ignition Switch-ST and Control Relay
System Schematic:
To test the Ignition Signal to the ECU, locate pins 102, 107 and 110. Test for the presence of battery voltage with the ignition key in the "on" position. There should be battery voltage present.
If no voltage is present, then test for battery voltage at the control relay pins 4, 5 and 10 and ignition switch. If no voltage is present, test relay or repair harness.
CONTROL RELAY
Control Relay:
Test control relay by removing relay and checking the following terminals of the control relay.
Caution
Use caution when connecting jumper wires to the relay. If they are incorrectly connected the relay will be damaged.
Fig. 1 Relay Test:
1. Connect jumper wires between relay terminals 10 and 8 and a 12v power source. Terminal 10 is positive (+) and 8 is negative (-).
2. Measure the voltage at terminals 4 and 5 with the power connected and disconnected at terminal 8.
POWER TO RELAY VOLTAGE READING TERMINALS 4 & 5
On System Voltage
Off 0 Volts
Fig. 2 Relay Test:
3. Connect jumper wires between relay terminals 9 and 6 and a 12v power source. Terminal 9 is positive (+) and 6 is negative (-).
4. Check for continuity at terminals 2 and 3 with the power connected and disconnected at terminal 6.
POWER TO RELAY CONTINUITY READING TERMINALS 2 & 3
On Continuity
Off No Continuity
Fig. 3 Relay Test:
5. Connect jumper wires between relay terminals 3 and 7 and a 12v power source. Terminal 3 is positive (+) and 7 is negative (-).
6. Measure the voltage at terminal 2 with the power connected and disconnected at terminal 7.
POWER TO RELAY VOLTAGE READING TERMINAL 2
On System Voltage
Off 0 Volts
7. Replace the control relay if it fails any of the previous tests.
HARNESS TEST
1. Disconnect the ECU connector and Turn on the ignition.
2. Using a voltmeter, measure the ignition switch terminal voltage between the ECU harness connector terminal 110 and ground.
Voltage: System Voltage.
3. Turn off the ignition and disconnect the control relay connector. Using a voltmeter, measure the power supply voltage between the harness connector terminal 10 and ground.
Voltage: System Voltage.
4. Check for continuity (short) to ground, between the control relay harness connector terminal 8 and the ECU harness connector terminals 66 and 63.
Continuity: Should Not Exist.
5. Check for continuity between the control relay harness connector terminal 8 and the ECU harness connector terminals 66 and 63.
Continuity: Should Exist.
6. Check for continuity (short) to ground, between the ECU harness connector terminals 102 and 107 and the control relay harness connector terminals 4 and 5.
Continuity: Should Not Exist.
7. Check for continuity between the ECU harness connector terminals 102 and 107 and their corresponding control relay harness connector terminals 4 and 5.
Continuity: Should Exist.
If any of the previous tests produce unsatisfactory results, the harness will need to be repaired or replaced. Once repairs have been completed, road test the vehicle to confirm that the repair has corrected the problem.
If the same problem reoccurs, it is possible that there is an intermittent failure of the component or the ECU. Check for looseness at all harness junctions and test for an intermittent failure.