Diagnostic Aids: Notes

WARNING: This page is about a different car, the 2004 GMC Sierra, 2004 GMC Cab & Chassis Sierra, 2004 Chevrolet Silverado, and 2004 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

CAUTION: Refer to Battery Disconnect Caution in Cautions and Notices.

CAUTION: To reduce the risk of severe shock and burns, always disconnect the 42 volt (42V) energy storage box (ESB) before doing any work to the ESB system. To disconnect the ESB, turn the engine off and turn OFF the service disconnect switch, which is located on the passenger side of the ESB.

IMPORTANT: The Panasonic HV1255 Valve Regulated Lead Acid (VRLA) batteries used in the PHT operate at a normal range of approximately 50 percent state of charge (SOC). If one or more of the batteries are diagnosed with a low charge or a battery fault and BEFORE battery replacement, the battery pack service charge procedure must be performed. Refer to Battery Pack Service Charge - HP2 . The new replacement battery will be delivered at approximately 80 percent SOC and must be charged alone to 100 percent SOC using the J 42634 battery module charger before installation.

All Panasonic batteries must be isolated or disconnected before testing or charging begins. Refer to Energy Storage Box (ESB) Power Cable Replacement - Battery 1 to Battery 2 (5.3L Engine w/RPO HP2) or Energy Storage Box (ESB) Power Cable Replacement - Battery 2 to Battery 3 (5.3L Engine w/RPO HP2) for proper battery isolation.

The Service Disconnect Switch must be turned to the OFF position from the energy storage box (ESB). Refer to Energy Storage Box (ESB) Service Disconnect/Connect (5.3L Engine w/RPO HP2) .

The 42-volt harness MUST also be disconnected at the ESB. Remove the red connector position assurance (CPA) retainer and disconnect the 42-volt positive/negative cable electrical connector. Refer to Positive and Negative Battery Cable (42V) Replacement (5.3L Engine w/RPO HP2) . This will ensure no power is present at the ESB, and no fuses or modules are affected during testing.

The Panasonic batteries in the Parallel Hybrid Truck (PHT) require both specific testing and charging procedures. Also the special service tools J 42000 and J 42000-30 must be used to gain proper results.

The battery test using the J 42000 requires correct connections to the battery terminals. Testing requires the use of the J 42000-30 to ensure a lead to lead contact between the battery and the test terminals and to be hand tighten only, overtightening will cause damage to the battery or test terminals. A failure to obtain the correct connections during the test may result in a failed test on a good battery.

For best results, use the J 42634 or equivalent automatic taper-rate battery charger with a voltage capability of 15.0 volts @ 12 amps max. set on automatic selection.
The charging area should be well ventilated.
Do not charge a battery that appears to be frozen. Allow the battery to warm to room temperature and test it before charging. Refer to Battery Inspection/Test (Non-HP2) or Battery Inspection/Test (HP2) .