Ignition Switch-ST and Control Relay

ECU Pin Connectors:

To test the Ignition Signal to the ECU, locate ECU pin 51. 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 8, 7, 3 and 5. If no voltage is present, test relay or repair harness.

Relay Schematic:

CONTROL RELAY

Caution: Use caution when connecting jumper wires to the relay. If they are incorrectly connected the relay will be damaged.

Relay Test:

Connect a 12v power source to control relay terminals 6 and 4. of the control relay coils.

Test the control relay by checking continuity between the following terminals

TERMINAL # CONTINUITY

1 - 7 Non Conductive (infinite Ohms)
2 - 5 Conductive (Approx 95 Ohms)
2 - 3 Conductive (Approx 95 Ohms)
6 - 4 Conductive (Approx 35 Ohms)

Remove the 12v power source from control relay terminals 6 and 4.
Test the control relay by checking continuity between the following terminals of the control relay coil.

TERMINAL # CONTINUITY

1 - 7 Conductive (0 Ohms)

Relay Test:

Connect a 12v power source to control relay terminals 8 and 4. of the control relay coils.

Test the control relay by checking continuity between the following terminals

TERMINAL # CONTINUITY

3 - 7 Non Conductive (infinite Ohms)
4 - 8 Conductive One Direction Only

Remove the 12v power source from control relay terminals 8 and 4.
Test the control relay by checking continuity between the following terminals of the control relay coil.

TERMINAL # CONTINUITY

3 - 7 Conductive (0 Ohms)



HARNESS TEST


1. Disconnect the control relay connector and Turn on the ignition.

2. Using a voltmeter, measure the ignition power supply voltage of the control relay, between harness connector terminal 8 and ground.

Voltage: System Voltage.

3.. Turn off the ignition. Using a voltmeter, measure the power supply voltage between the harness connector terminal 7 and ground.

Voltage: System Voltage.

4. Check for continuity of the ground circuit, between harness connector terminal 4 and ground.

Continuity: Should Exist.


5. Check for continuity (short) to ground, between the ECU harness connector terminal 51 and the control relay harness connector terminal 5.

Continuity: Should Not Exist.

6. Check for continuity between the ECU harness connector terminal 51 and the control relay harness connector terminal 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.