P1483

P1483-STARTER RELAY 2 STUCK OFF

For a complete wiring diagram, refer to the Wiring Information.





Theory of Operation

The Engine Stop/Start (ESS) system uses an In-Rush Current Relay (ICR) to reduce the voltage drop during an Auto Start event. The purpose of this is for the consumer electronics and vehicle subsystems to continue to function in a normal manner. The ICR is connected in-line of the main Battery feed to the Starter Motor.

The ICR is normally closed in the off position. This means that when it is de-energized, the relay is closed and full battery current is allowed to pass through the ICR directly to the Starter Motor with no resistance. During all key crank events the ICR is in this mode of operation and voltage drop is approximately 3.5 volts during cranking.

However, during an Auto Start crank event in ESS mode, the ICR is energized which opens the relay. When this occurs, battery current to the Starter Motor is diverted through the resistor inside the ICR and then to the Starter Motor. This reduces the voltage drop from approximately 2.0 volts during an Auto Start cranking event.

The ICR is energized when 12 volts is supplied to the coil by the ICR Control Relay, which is controlled the Powertrain Control Module (PCM).

- When Monitored:
The Powertrain Control Module (PCM) monitors the voltage drop of the Battery during any start event. This diagnostic is run during an Auto Start event.

- Set Conditions:
The Powertrain Control Module (PCM) sees the battery voltage drop more than a calibrated threshold (approximately 2.5 volts) during an Auto Start event.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.

Diagnostic Test

1. CHECK BATTERY
1. Using the approved Battery tester, check the Battery condition.

Did the Battery pass the load test?

Yes

- Go To 2

No

- Replace the Battery and retest.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

2. ACTIVE DTC
1. Test drive the vehicle and perform several auto starts of the engine.
2. With the scan tool, read DTCs.

Is the DTC active?

Yes

- Go To 3

No

- Perform the INTERMITTENT CONDITION diagnostic procedure. Intermittent Condition Test.

3. CHECK THE (T760) IN-RUSH RELAY CONTROL CIRCUIT FOR A SHORT TO GROUND
1. Turn the ignition off.
2. Disconnect the PDC C3 harness connector.
3. Disconnect the ICR Relay C1 harness connector.
4. Measure the resistance between ground and the (T760) In-Rush Relay Control circuit at the ICR Relay C1 harness connector.

Is the resistance above 10k Ohms?

Yes

- Go To 4

No

- Repair the (T760) In-Rush Relay Control circuit for a short to ground.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

4. CHECK THE (T760) IN-RUSH RELAY CONTROL CIRCUIT FOR AN OPEN/HIGH RESISTANCE
1. Measure the resistance of the (T760) In-Rush Relay Control circuit between the In-Rush Current Relay and the PDC C3 harness connector.

Is the resistance below 5.0 Ohms?

Yes

- Repair the (T760) In-Rush Relay Control circuit for an open or high resistance.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 5

5. CHECK THE IN-RUSH CURRENT RELAY
1. Reconnect the PDC C3 harness connector.
2. Turn the ignition on.
3. Remove the (A11) Fused Battery Cable from the In-Rush Current Relay.
4. Remove the (A8) Battery Starter Feed Cable from the In-Rush Current Relay.

NOTE:
These are live Battery Feeds. Be careful to insulate and/or isolate the cable so that it cannot make contact with any engine ground.

5. Measure the resistance across the terminals of the In-Rush Current Relay.

NOTE:
The relay is normally closed when not energized and therefore not passing through the resistor inside the relay.

6. While continuing to measure the resistance across the terminals of the relay, supply 12 volts to the terminal that the (T760) In-Rush Relay Control circuit connects to at the In-Rush Current relay. When the 12 volt supply is removed, the resistance should change back to below 2.0 Ohms if the relay is not stuck open.

NOTE:
This will energize the relay which will open the direct path and cause the current to flow through the internal resistor.

Did the resistance change from below 2.0 Ohms to significantly higher when the In-Rush Current Relay was energized?

Yes

- The In-Rush Current Relay is not stuck closed at this time. This may be an intermittent condition. Try energizing and de-energizing the relay several times while testing continuity across the relay to check for an intermittent stuck condition.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Replace the In-Rush Current Relay.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.