Ignition Relay Diagnosis
Diagnostic Instructions
Circuit/System Description
The powertrain relay is controlled by the engine control module
(ECM) depending upon input from the ignition switch. Battery
positive voltage is supplied to the relay coil and switch. When the
ignition switch is turned to the ON position, the ECM will provide
ground on the control circuit of the powertrain relay using a low
side driver. This will allow voltage through the relay switch
contacts to the components. The ECM monitors the voltage level on
the control circuit of the powertrain relay.
Reference Information
Schematic Reference
Engine Controls Schematics
Connector End View Reference
Component Connector End Views
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Special Tools
EL 43244 Relay Puller Pliers
For equivalent regional tools, refer to
Special Tools .
Circuit/System Verification
| 1. |
Cycle the ignition from OFF to
ON. You should hear and feel an audible click from the KR75
Powertrain Relay. Repeat as necessary in order to verify KR75
Powertrain Relay operation. |
| 2. |
Operate the vehicle within the
Conditions for Running the DTC to verify the DTC does not reset.
You may also operate the vehicle within the conditions that you
observed from the Freeze Frame/Failure Records data. |
Circuit/System Testing
| 1. |
Ignition OFF, disconnect the
KR75 Powertrain Relay. |
| 2. |
Ignition ON, verify a test
lamp illuminates between the B+ circuit terminal 30 and
ground. |
| ⇒ |
If the test lamp does not illuminate, test the B+
circuit for a short to ground or an open/high resistance. Replace
the fuse if necessary. |
| 3. |
Ignition OFF, connect a test
lamp between the control circuit terminal 86 and the B+ circuit
terminal 30. |
| ⇒ |
If the test lamp is always ON, test the control
circuit for a short to ground. If the circuit tests normal, replace
the K20 Engine Control Module. |
| 4. |
Ignition ON. The test lamp
should turn ON. |
| ⇒ |
If the test lamp is always OFF, test the control
circuit for a short to voltage or an open/high resistance. If
circuit tests normal, replace the K20 Engine Control Module. |
| 5. |
Install a 20 A fused jumper
wire between the B+ circuit terminal 87 and the ignition circuit
terminal 85. |
| 6. |
Attempt to start the engine.
The engine should start. |
| ⇒ |
If the engine does not start, test the ignition
circuit between the KR75 Powertrain Relay and the K20 Engine
Control Module for a short to ground or for an open/high
resistance. If the circuit tests normal, replace the K20 Engine
Control Module. |
| 7. |
If all circuits test normal,
test or replace the KR75 Powertrain Relay. |
Component Testing
Relay Test
| 1. |
Ignition OFF, disconnect the
KR75 Powertrain Relay. |
| 2. |
Test for 70-110 Ω
between terminal 85 and 86. |
| ⇒ |
If not within the specified range, replace the
KR75 Powertrain Relay. |
| 3. |
Test for infinite resistance
between the following terminals of the KR75 Powertrain
Relay: |
| ⇒ |
If not the specified value, replace the KR75
Powertrain Relay. |
| 4. |
Install a 20 A fused jumper
wire between relay terminal 85 and 12 V. Install a jumper wire
between relay terminal 86 and ground. Test for less than 5 Ω
between terminal 30 and 87. |
| ⇒ |
If greater than the specified range, replace the
KR75 Powertrain Relay. |
Repair Instructions
Perform the
Diagnostic Repair Verification after completing the diagnostic
procedure.
|
