LOCK 9D9797 - Caterpillar

System Operation Description:Use this procedure to troubleshoot a suspected problem with an ignition transformer. Also use this procedure if one of the diagnostic codes in Table 1 or Table 2 are active or easily repeated.
Table 1
Diagnostic Codes Table
Code and Description Conditions which Generate this Code System Response
1268-5 Engine Ignition Coil #1 : Current Below Normal
1269-5 Engine Ignition Coil #2 : Current Below Normal
1270-5 Engine Ignition Coil #3 : Current Below Normal
1271-5 Engine Ignition Coil #4 : Current Below Normal
1272-5 Engine Ignition Coil #5 : Current Below Normal
1273-5 Engine Ignition Coil #6 : Current Below Normal While the engine is started, the Electronic Control Module (ECM) detects a low current flow in the primary circuit for the ignition transformer. The code is logged.
The amber warning lamp is illuminated.
The red stop lamp is illuminated.
Table 2
Diagnostic Codes Table
Code and Description Conditions which Generate this Code System Response
1268-6 Engine Ignition Coil #1 : Current Above Normal
1269-6 Engine Ignition Coil #2 : Current Above Normal
1270-6 Engine Ignition Coil #3 : Current Above Normal
1271-6 Engine Ignition Coil #4 : Current Above Normal
1272-6 Engine Ignition Coil #5 : Current Above Normal
1273-6 Engine Ignition Coil #6 : Current Above Normal While the engine is started, the ECM detects an excessive current flow in the primary circuit for the ignition transformer. The code is logged.
The amber warning lamp is illuminated.
The red stop lamp is illuminated. Note: The engine must be running in order for the above diagnostic codes to become active.Systems OperationThe ECM has internal power circuits that are used to energize the primary circuits for the ignition transformers. Each power circuit creates a signal of 108 v. The signal is sent from the ECM to the primary circuits of the ignition transformers. The secondary circuits for the ignition transformers deliver high voltage (8,000 to 37,000 v) to the spark plugs. The external ignition wiring is continuous from the ECM connector to each terminal that is for the ignition transformers.Some power circuits and returns are shared. Therefore, a single problem will generate either only one diagnostic code or multiple codes.Power and Return for the Ignition Transformer PrimaryThe power circuits that are internal to the ECM send signals to more than one cylinder. For this reason, a high side short circuit or a low side short circuit may affect more than one cylinder.The return circuits that are internal to the ECM send signals to a single cylinder.For the combinations of cylinders that can be affected by a condition, refer to Table 3.
Table 3
Diagnostic Conditions and the Combinations of Cylinders that are Affected
Diagnostic Condition Cylinders
The power circuit for a single transformer shorted to the return circuit for that transformer. Only one cylinder is affected.
Short to engine ground for the power circuit