Crank, No Start, Stall, Hard Start, and No Cranking RPM - kw nostart nocrank 4.3 4.8 5.3 6.0 8.1 ignition information injector L18 L59 LM7 LQ4 LQ9 LR4 LU3 PCM L33

The following diagnosis might be helpful if the vehicle exhibits the symptom described in the PI.

Crank no start, stalling, hard start, loss of cranking RPM, or loss of ignition 1 voltage. Depending on the model and the conditions present DTCS B3031, P0120, P0220, P0135, P0141, P0155, P0161, P1516, P1631, P2101 P2135, U1016 and U1064 may also be stored. It may also be noted that normal crank RPM registers momentarily as the key is released from the crank position.

If the "Engine Cranks but Does Not Run" SI diagnostics did not isolate a concern, the following information may help: Using the Tech 2, monitor the Ignition 1 voltage parameter when the customer concern is duplicated. With a fully charged battery, the Ignition 1 voltage parameter should not drop below 10 volts while cranking. If it does, measure the main voltage supply to the Underhood Bussed Electrical Center (UBEC) during the condition. If the UBEC voltage supply is above 10 volts but the Tech 2 Ignition 1 Voltage Parameter is below 10 volts, replace the Ignition 1 Relay.

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Please follow this diagnosis process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed. If these steps do not resolve the condition, please contact GM TAC for further diagnostic assistance.

(03 04 05 Cadillac Escalade C1, C6, K1, K6) and ( 03 04 05 Chevrolet Avalanche C1, K1, C2, K2) and ( 03 04 05 Chevrolet Silverado Truck C1, K1, C2, K2, C3, K3) and ( 03 04 05 Chevrolet Tahoe C1, K1 ) and ( 03 04 05 Chevrolet Suburban C1, K1, C2, K2, C3, K3 ) and ( 03 04 05 GMC Sierra Truck C1, K1, C2, K2, C3, K3 ) and ( 03 04 05 GMC Yukon C1, K1 ) and ( 03 04 05 GMC Yukon XL C1, K1, C2, K2, C3, K3) and (03 04 05 Hummer H2 N2 )

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