P1A70

DTC P1A70

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions) provides an overview of each diagnostic category.

DTC Descriptor
DTC P1A70
- Starter/Generator Control Module System Voltage Performance

Circuit/System Description

The starter/generator control module (SGCM) monitors the performance to detect 12-volt DC wire electrical failure by comparing the 12-volt input to the 12-volt output values. If the difference is greater than 5 volts, the DTC sets.

Conditions for Running the DTC

* The engine is running.
* Hybrid mode is active.

Conditions for Setting the DTC

The 12-volt power supply - 12-volt output voltage is greater than 5 volts for 119 ms and any fault during 15 seconds wait period.

Action Taken When the DTC Sets

* Stop PWM (MGU shutdown).
* APM PWM off.

Conditions for Clearing the DTC

Cycle wake up signal.

Diagnostic Aids

Possible 12-volt battery or APM voltage sensor stuck.

Reference Information
Schematic Reference

Hybrid Controls Schematics (Hybrid Controls Schematics)
Connector End View Reference

Component Connector End Views (Connector End Views By Name)
Description and Operation

Starter/Generator Description and Operation (Description and Operation)
Electrical Information Reference

* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)

Scan Tool Reference

Control Module References (Programming and Relearning) for scan tool information

Circuit/System Testing

Caution: To help avoid personal injury, additional precautions must be taken prior to working on the generator control module or the generator starter. After removing the 36V battery cables from the generator battery, remove both engine wiring harness connectors from the generator control module. Wait at least 5 minutes and then remove the generator control module cover. Verify voltage levels at all 36V, 12V, and 3-phase connections, are less than 3 volts using a DMM before proceeding.

Note: If a battery charger is connected to the vehicle, disconnect it now.

1. Measure and record the voltage at the SGCM signal connector B+ and Ignition circuits and compare them to the voltage at the 12V battery.

• If the measurements vary by more than 1V, check the circuits for a open/high resistance.

2. Inspect all B+ and Ignition connections from the SGCM to each fuse block and the 12V battery.
3. With a scan tool, clear the DTC.
4. Ignition OFF, wait 30 seconds.
5. Ignition ON, operate the vehicle within the Conditions for Running the DTC and verify the DTC does not reset.

• If the DTC resets, replace the SGCM.

Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

Control Module References (Programming and Relearning) for SGCM replacement, setup, and programming