Diagnostic Fault Information
Always perform the
Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
Typical Scan Tool Data
EC Ignition Relay Feedback Signal
Circuit
| Normal Range
| Short to Ground
| Open
| Short to Voltage
|
Operating Conditions:
Ignition ON, with the engine OFF
|
B+ Supply Voltage - Coil
| --
| 0.0 V
| 0.0 V
| --
|
B+ Supply Voltage - Armature
| --
| 0.0 V
| 0.0 V
| --
|
EC Ignition Relay Control
| --
| 0.0 V
| 0.0 V
| --
|
EC Ignition Relay Feedback
| 11.9-12.9 V
| 0.0 V
| 0.0 V
| More than 2 V¹
|
Circuit/System Description
The powertrain relay is a normally open relay. The relay armature is held in the open position by spring tension. Battery positive voltage is supplied directly to the relay coil and the armature contact at all times. The engine control module (ECM) supplies
the ground path to the relay coil control circuit via an internal integrated circuit called an output driver module (ODM). The ODM output control is configured to operate as a low side driver for the powertrain relay. The ODM for the powertrain relay also incorporates
a fault detection circuit, which is continuously monitored by the ECM. When the ECM commands the powertrain relay ON, ignition 1 voltage is supplied to the following fuses and relay in the underhood fuse block:
The ignition 1 voltage that is supplied to the ECM through the ETC/ECM fuse, provides power to the internal ECM circuits associated with the throttle actuator control (TAC) operation. The ECM also monitors the voltage level on the ignition 1
voltage circuit to confirm that the powertrain relay contacts have closed.
Diagnostic Aids
| • | This test procedure requires that the vehicle battery has passed a load test and is completely charged. Refer to
Battery Inspection/Test . |
| • | When disconnecting electrical connectors or removing fuses and relays from a fuse block, always inspect the component electrical terminals for corrosion and the mating electrical terminals for tightness. |
| • | Use the
J 35616 Connector Test Adapter Kit for any test that requires probing the underhood fuse block terminals, component wire harness terminals, or the ECM wire harness connector terminals. |
Reference Information
Schematic Reference
Engine Controls Schematics
Connector End View Reference
Electrical Information Reference
Scan Tool Reference
Special Tools Required
J 43244 Relay Puller Pliers
Circuit/System Verification
- With the ignition ON, engine OFF, command the powertrain relay ON and OFF several times using the scan tool output control function. You should either hear or feel the relay click with each command.
- With the ignition ON, engine OFF, probe both test points of each of the following fuses:
| ⇒ | The test lamp should illuminate on at least one test point of each fuse. If the test lamp does not illuminate continue with Circuit/System Testing. |
Circuit/System Testing
- With the ignition OFF, remove the powertrain relay from the underhood fuse block.
- With the ignition ON, measure for battery positive voltage (B+) between the relay coil voltage supply circuit and ground.
| ⇒ | If the voltage measures less than B+, repair the open or high resistance in the circuit to the relay coil. All wire circuit resistance should measure less than 2 ohms. |
- Measure for voltage between the relay coil control circuit and ground.
| ⇒ | If voltage is measured on the control circuit of the relay, test for a short to voltage or a faulty ECM. |
- Connect a test lamp between the battery positive voltage supply circuit of the relay coil and the relay coil control circuit at the underhood fuse block. Use a scan tool to command the powertrain relay ON and OFF. The test lamp should turn ON and
OFF when toggling between the commanded states.
| ⇒ | If the test lamp stays ON all the time, test for a short to ground on the relay coil control circuit or a faulty ECM. |
| ⇒ | If the test lamp stays OFF all the time, test for an open or high resistance on the relay coil
control circuit or a faulty ECM. All wire circuit resistance should measure less than 2 ohms. |
- Measure for B+ between the relay armature supply circuit, and ground.
| ⇒ | If the voltage measures less than B+, repair the open or high resistance in the circuit to the relay armature. All wire circuit resistance should measure less than 2 ohms. |
- With the ignition ON, test for voltage on each test point of the ETC/ECM fuse in the underhood fuse block.
| ⇒ | If voltage is present, test the ignition 1 voltage circuit between the ECM, the powertrain relay, and the ETC/ECM fuse for a short to voltage. |
| ⇒ | If both circuits test normal, replace the ECM. |
- Connect a 20-amp fused jumper wire between the B+ terminal and the ignition 1 voltage terminal of the powertrain relay at the underhood fuse block. With a test lamp, probe both test points of the ETC/ECM fuse.
| ⇒ | If the test lamp illuminates at both test points of the ETC/ECM fuse, repair the ignition 1 voltage circuit between the powertrain relay and the ECM for an open , high resistance, or a faulty ECM. All wire circuit resistance should
measure less than 2 ohms. |
| ⇒ | If the test lamp only illuminates at one test point of the ETC/ECM fuse, repair the short to ground in the ignition 1 voltage circuit between the fuse and the applicable component. Replace the
fuse as necessary. |
| ⇒ | If the test lamp does not illuminate on either test point of the ETC/ECM fuse, repair the open or high resistance between the powertrain relay and the ETC/ECM fuse. All wire circuit resistance should measure 2 ohms or less. |
- With a test lamp, test for voltage on both test points of the following fuses:
| ⇒ | If the test lamp fails to illuminate on one test point of each fuse, repair the open or high resistance between the fuse and the powertrain relay. All wire circuit resistance should measure 2 ohms or less. |
Component Testing
| • | Measure for 70-110 ohms between terminals 85 and 86 of the relay. |
| ⇒ | If the resistance is not within the specified range, replace the relay. |
| • | Measure for infinite resistance between terminals 30 and 86 of the relay. |
| ⇒ | If continuity is detected, replace the relay. |
| • | Measure for infinite resistance between terminals 30 and 87 of the relay. |
| ⇒ | If continuity is detected, replace the relay. |
| • | Measure for infinite resistance between terminals 30 and 85 of the relay. |
| ⇒ | If continuity is detected, replace the relay. |
| • | Measure for infinite resistance between terminals 85 and 87 of the relay. |
| ⇒ | If continuity is detected, replace the relay. |
| • | Connect a 20-amp fused jumper wire from the battery positive cable at the battery, to relay terminal 85. Connect a jumper wire from the negative battery cable at the battery, to relay terminal 86. Measure for less than 2 ohms
between terminals 30 and 87 of the relay, with a DMM. |
| ⇒ | If the resistance measures more than 2 ohms, replace the relay. |
Repair Instructions
Important: Always perform the
Diagnostic Repair Verification after completing the diagnostic procedure.
