Voltage Signal: Testing and Inspection

Ignition-IG And Control Relay:

To test the Ignition Signal to the ECU, locate ECU pin 107. 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 and 8, 2, and 3. If no voltage is present, test relay or repair harness.





CONTROL RELAY

Fig. 1 Control Relay:

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

Test control relay by checking continuity between the following terminals of the control relay coil.

TERMINAL # CONTINUITY

3 - 5 Conductive (Approx 95 Ohms)
2 - 5 Conductive (Approx 95 Ohms)
6 - 7 Conductive (Approx 35 Ohms)
6 - 8 Conductive in one direction only

Control Reley Test Schematic:

Test the continuity of the control relay contacts between terminals 1 - 4 by connecting a 12 volt power source to terminals 6 - 7 and testing for continuity at terminals 1 - 4.

RELAY CONDITION CONTINUITY

NOT ENERGIZED non-conductive (infinite Ohms)
ENERGIZED conductive (0 Ohms)

Test the continuity of the control relay contacts between terminals 2 - 4 by connecting a positive side 12 volt power source to terminal 8 and the negative side to terminal 6. Check for continuity at terminals 2 - 4.

RELAY CONDITION CONTINUITY

NOT ENERGIZED nonconductive (infinite Ohms)
ENERGIZED conductive (0 Ohms)

Relay Test:

Test the continuity of the control relay contacts between terminals 1 - 4 by connection a 12 volt power source to terminals 2 - 5 and testing for continuity at terminals 1 - 4.

RELAY CONDITION CONTINUITY

NOT ENERGIZED nonconductive (infinite Ohms)
ENERGIZED conductive (0 Ohms)

If the control relay fails any of the tests, it must be replaced.

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 4 and ground.

Voltage: System Voltage.

4. Check for continuity of the ground circuit, between harness connector terminal 6 and ground.

Continuity: Should Exist.


5. Check for continuity (short) to ground, between the ECU harness connector terminal 107 and the control relay harness connector terminal 3.

Continuity: Should Not Exist.
.
6. Check for continuity between the ECU harness connector terminal 107 and the control relay harness connector terminal 3.

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.