TRANSMISSION CONTROL GROUP 2V9378 - Caterpillar

Illustration 3 g01186024
Location of the J1/P1 ECM connectors (typical left side engine view)
Thoroughly inspect the J1/P1 ECM connectors, the firewall bulkhead connector, and the terminals for the tachometer in the connectors. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
Illustration 4 g01259221
Terminal locations at the P1 ECM connector for the tachometer circuit
(P1-38) Tachometer +
(P1-39) Tachometer −
Perform a 45 N (10 lb) pull test on each of the wires in the ECM connector that are associated with the terminals for the tachometer.
Check the allen head screw for each of the ECM connectors for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for the correct torque values.
Check the harness and wiring for abrasion and for pinch points from the battery to the ECM. Expected Result:All connectors, pins and sockets are completely coupled and/or inserted and the harness and wiring are free of corrosion, of abrasion or of pinch points.Results:
OK - The harness and connectors appear to be OK. Proceed to Test Step 4.
Not OK - There is a problem with the connectors and/or wiring.Repair: Repair the connectors or wiring and/or replace the connectors or wiring. Ensure that all of the seals are properly in place and ensure that the connectors are completely coupled.Verify that the repair eliminates the problem.STOPTest Step 4. Check the ECM Connection to the Tachometer
Inspect the J1/P1 ECM connector. Verify that the connections are present at P1-39 Tachometer − and/or P1-38 Tachometer +. Note: Some of the tachometers require only one signal line to be connected. Either of the ECM terminals can be used for this type of tachometer. The other wire should be left disconnected. If both wires are connected, and one indicates an open circuit, repair this line.Expected Result:Wires are connected to the ECM terminals for the tachometer, P1-39 (Tachometer −) and/or P1- 38 (Tachometer +).Results:
OK - The ECM is providing the signal for the tachometer. Proceed to Test Step 5.
Not OK - The ECM is not connected in order to supply the signal to the tachometer.Repair: Send the vehicle to the OEM dealer in order to repair the tachometer circuit.STOPTest Step 5. Check the Tachometer Signal at ECMNote: Performing certain steps within this procedure requires the use of a multimeter that is capable of measuring a PWM Duty Cycle.
Turn the keyswitch to the OFF position.
Disconnect the J1/P1 ECM connector.
Remove the wire in P1-38 Tachometer + from the ECM connector P1.
Remove the wire in P1-39 Tachometer − from the ECM connector P1.
Fabricate two jumper wires that are long enough to create a test circuit at the breakout T. Crimp connector pins to one end of each of the jumper wires.
Install a 208-0059 Adapter Cable As (70-PIN BREAKOUT) to the ECM vehicle harness connector J1/P1.
Insert one of the jumper wires into terminal location 39 (Tachometer −) of the breakout T and insert the other jumper wire into terminal location 38 (Tachometer +) of the breakout T.
Access the "Tachometer Circuit Test". Access the following display screens in order:
"Diagnostics"
"Diagnostic Tests"
"Special Test"
Attach the positive lead of the multimeter