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Battery 1 Voltage – Data Valid but Above Normal Operational Range – Moderately Severe Level
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Overview
| CODE | REASON | EFFECT |
| Fault Code: 442 PID: P168 SPN: 168 FMI: 0/16 LAMP: Amber SRT: |
Battery 1 Voltage – Data Valid but Above Normal Operational Range – Moderately Severe Level. ECM supply voltage is above the maximum system voltage level. |
Possible electrical damage to all electrical components. |
 ISX and ISM – Unswitched Battery Supply Circuit
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Circuit Description
The electronic control module (ECM) receives constant voltage from the batteries through the unswitched battery wires that are connected directly to the positive (+) battery post. There is one 30-ampere fuse in the unswitched battery wire to protect the OEM harness. The ECM receives switched battery input through the vehicle keyswitch wire when the vehicle keyswitch is turned on. The battery return wires are connected directly to the negative (-) battery post.
Component Location
The ECM is located on the intake side of the engine. Refer to Procedure 100-002 (Engine Diagrams) in Section E for a detailed component location view. The ECM is connected to the battery by the OEM harness. This direct link provides a constant power supply for the ECM. The location of the battery will vary with the original equipment manufacturer (OEM). Refer to the OEM troubleshooting and repair manual for battery location.
Conditions for Running the Diagnostics
This diagnostic runs continuously when the keyswitch is in the ON position or when the engine is running.
Conditions for Setting the Fault Codes
The ECM detects that the main battery supply voltage is greater than +36-VDC.
Action Taken When the Fault Code is Active
- The ECM logs the fault code immediately when the diagnostic runs and fails.
Conditions for Clearing the Fault Code
The ECM will turn off the fault code immediately after the battery voltage drops below +36-VDC.
Shop Talk
Verify the electronic control module (ECM) calibration is correct. Check the calibration revision history found on QuickServe® Online for applicable fixes to the calibration stored in the ECM. If necessary, recalibrate the ECM. Refer to Procedure 019-032 (ECM Calibration Code) in Section 19 in the corresponding Troubleshooting and Repair Manual for the engine being serviced.
This fault code is logged when the ECM battery supply voltage exceed +36-VDC. Causes of this fault code include:
- Faulty alternator or regulator that is overcharging the system
- Batteries connected in series instead of parallel
- Incorrect jump-starting procedure.
Refer to Troubleshooting Fault Code t05-442
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