When undertaking a 5.9L engine swap into a Jeep ZJ, proper wiring is crucial for ensuring your transmission control module (TCM) functions correctly. This guide, adapted from expert resources, details the necessary wiring connections, focusing on the essential “5.9 Zj Obd2 Wire” setup for your project. Accurate wiring is not just about getting your vehicle running; it’s about optimizing performance and reliability after your 5.9 swap. This document provides a clear, step-by-step approach to wiring the TCM, ensuring a smooth integration with your ZJ.
Gray 8-Prong Connector Wiring
This section outlines the connections for the gray 8-prong connector from your transmission body. These wires are vital for shifter position sensing, feeding information to the TCM about your gear selection.
-
Pin 1: TRS 1-2 Sense (Violet with White Stripe Wire)
- Connection: Connect this wire to Pin 21 on the TCM plug.
- Function: Signals to the TCM that the shifter is in the 1-2 range by applying 12 volts. This is also referred to as TRS T42 sense.
-
Pin 2: TRS 3 Sense (Violet Wire)
- Connection: Connect this wire to Pin 9 on the TCM plug.
- Function: Informs the TCM that the shifter is in the 3 range by sending a 12-volt signal.
-
Pin 3: Fused Ignition Switch Output (Run-Start) (White Wire)
- Connection: Connect this wire to the wire bundle from the TJ PCM, specifically connector 1 pin A2.
- Function: Provides power to the TRS when the ignition key is in the run or start position. This power enables the TRS to send range signals to the TCM.
-
Pin 4: TRS Overdrive Sense (Light Green with Black Stripe Wire)
- Connection: Connect this wire to Pin 22 on the TCM plug.
- Function: Signals the TCM that the shifter is in overdrive (OD) range by applying 12 volts.
-
Pin 5: (Not Used)
- Function: This pin is not utilized in this configuration.
-
Pin 6: TRS Reverse Sense (Brown with Light Green Stripe Wire)
- Connection: Connect this wire to Pin 18 on the TCM plug.
- Function: Signals the TCM when the shifter is in reverse, applying 12 volts to pin 18. This is also known as the Back Up Lamp Feed.
-
Pin 7: Park/Neutral Position Switch Sense (Black with White Stripe Wire)
- Connection: Connect this wire to the wire bundle from the TJ PCM, connector 1 pin A6.
- Function: Grounds the Park/Neutral circuit on the TJ harness when in Park or Neutral, allowing the starter relay to engage and the engine to start.
-
Pin 8: Ground (Black Wire)
- Connection: Connect this wire to the wire bundle from the TJ PCM, connector 1 pin 31 or 32.
- Function: Provides the necessary ground to complete the Park/Neutral circuit.
Black 8-Prong Connector Wiring
This section details the wiring for the black 8-prong connector, which is critical for transmission speed sensor signals and solenoid control. These “5.9 zj obd2 wire” connections are essential for the TCM to manage gear shifts and torque converter lockup.
-
Pin 1: Input Speed Sensor Signal (Red with Black Stripe Wire)
- Connection: Connect this wire to Pin 2 on the TCM plug.
- Function: Sends the input speed sensor signal to the TCM, indicating the transmission’s input RPM.
-
Pin 2: Transmission Solenoid B (Orange with White Stripe Wire)
- Connection: Connect this wire to Pin 13 on the TCM plug.
- Function: Controls Transmission Solenoid B, used by the TCM for shifting gears.
-
Pin 3: Transmission Solenoid A (White Wire)
- Connection: Connect this wire to Pin 12 on the TCM plug.
- Function: Controls Transmission Solenoid A, also used by the TCM for gear changes.
-
Pin 4: Transmission Solenoid C (Lockup) (Dark Blue with White Stripe Wire)
- Connection: Connect this wire to Pin 11 on the TCM connector.
- Function: Controls Transmission Solenoid C, which the TCM uses to engage and disengage the torque converter lockup.
-
Pin 5: Input Speed Sensor Ground (Violet with Light Green Stripe)
- Connection: Connect this wire to Pin 1 on the TCM plug.
- Function: Completes the circuit for the input speed sensor.
-
Pin 6: Output Speed Sensor Ground (Dark Blue with Black Stripe Wire)
- Connection: Connect this wire to Pin 3 on the TCM plug.
- Function: Completes the circuit for the output speed sensor.
-
Pin 7: Output Speed Sensor Signal (Light Green with White Stripe Wire)
- Connection: Connect this wire to Pin 4 on the TCM plug.
- Function: Sends the output speed sensor signal to the TCM, indicating the transmission’s output RPM.
-
Pin 8: (Not Used)
- Function: This pin is not used in this application.
Black 26-Prong Connector to TCM Wiring
The black 26-prong connector is the main interface to the TCM. These “5.9 zj obd2 wire” connections manage sensor inputs, solenoid controls, and power supply for the TCM. Proper wiring here is paramount for the electronic control of your transmission after the 5.9 swap.
-
Pin 1: Input Speed Sensor Ground (Violet with Light Green Stripe)
- Connection: Connect this wire to Pin 5 on the black 8-way plug.
- Function: Completes the input speed sensor circuit.
-
Pin 2: Input Speed Sensor Signal (Red with Black Stripe Wire)
- Connection: Connect this wire to Pin 1 on the black 8-way plug.
- Function: Sends the input speed sensor signal to the TCM.
-
Pin 3: Output Speed Sensor Ground (Dark Blue with Black Stripe Wire)
- Connection: Connect this wire to Pin 6 on the black 8-way plug.
- Function: Completes the output speed sensor circuit.
-
Pin 4: Output Speed Sensor Signal (Light Green with White Stripe Wire)
- Connection: Connect this wire to Pin 7 on the black 8-way plug.
- Function: Sends the output speed sensor signal to the TCM.
-
Pin 5: (Not used)
- Function: Not utilized.
-
Pin 6: CCD BUS (-) (NOT USED!)
- Function: Not used in this application.
-
Pin 7: CCD BUS (+) (NOT USED!)
- Function: Not used in this application.
-
Pin 8: (Not used)
- Function: Not utilized.
-
Pin 9: TRS T3 Sense (TRS 3 Sense) (Violet Wire)
- Connection: Connect this wire to Pin 2 on the gray 8-way plug.
- Function: Signals the TCM that the shifter is in the 3 range.
-
Pin 10: (Not used)
- Function: Not utilized.
-
Pin 11: Transmission Solenoid C (Lockup) (Dark Blue with White Stripe Wire)
- Connection: Connect this wire to Pin 4 on the black 8-way plug.
- Function: Controls Transmission Solenoid C (lockup).
-
Pin 12: Transmission Solenoid A (White Wire)
- Connection: Connect this wire to Pin 3 on the black 8-way plug.
- Function: Controls Transmission Solenoid A.
-
Pin 13: Transmission Solenoid B (Orange with White Stripe Wire)
- Connection: Connect this wire to Pin 2 on the black 8-way plug.
- Function: Controls Transmission Solenoid B.
-
Pin 14: (Not used)
- Function: Not utilized.
-
Pin 15: (Not used)
- Function: Not utilized.
-
Pin 16: Sensor Return (Sensor Ground) (Brown with Yellow Stripe Wire)
- Connection: Connect this wire to the wire bundle from the TJ PCM, connector 1 pin A4.
- Function: Provides sensor ground back to the TJ PCM, completing the circuit for TPS and brake switch signals.
-
Pin 17: Throttle Position Sensor Signal (Orange with Dark Blue Stripe Wire)
- Connection: Connect this wire to the wire bundle from the TJ PCM, connector 1 pin A23.
- Function: Sends the throttle position sensor signal to the TCM, used for calculating shift points.
-
Pin 18: Back Up Lamp Feed (TRS Reverse Sense) (Brown with Light Green Stripe Wire)
- Connection: Connect this wire to Pin 6 on the gray 8-way plug.
- Function: Signals reverse gear to the TCM and acts as the Back Up Lamp Feed.
-
Pin 19: (Not used)
- Function: Not utilized.
-
Pin 20: (Not used)
- Function: Not utilized.
-
Pin 21: T42 Sense (TRS 1-2 Sense) (Violet with White Stripe Wire)
- Connection: Connect this wire to Pin 1 on the gray 8-way plug.
- Function: Signals the TCM that the shifter is in the 1-2 range.
-
Pin 22: TRS T1 Sense (TRS Overdrive Sense) (Light Green with Black Stripe Wire)
- Connection: Connect this wire to Pin 4 on the gray 8-way plug.
- Function: Signals the TCM that the shifter is in the OD range.
-
Pin 23: Brake Switch Sense (White with Pink Stripe Wire)
- Connection: Connect this wire to the wire bundle from the TJ PCM, connector 3 pin C24.
- Function: Informs the TCM when the brakes are applied.
-
Pin 24: Ground (Black with Tan Strip Wire)
- Connection: Connect this wire to the wire bundle from the TJ PCM, connector 1 pin A31 or A32.
- Function: Provides ground for the TCM.
-
Pin 25: Fused B (+) (Pink 20 Gauge Wire)
- Connection: Run this wire directly to the battery positive terminal with an inline 15A fuse.
- Function: Provides constant power for the TCM.
-
Pin 26: Fused Ignition Switch Input (Start-Run) (Dark Blue with White Stripe Wire)
- Connection: Connect this wire to the wire bundle from the TJ PCM, connector 1 pin A2.
- Function: Provides power to the TCM when the ignition is in the run or start mode.
The TCM is typically mounted under the center console, above the airbag computer, beneath the armrest. Wires can be routed along the transmission tunnel and up the firewall to the PCM. Remember to adapt grounding for starting and reverse lamps as needed for your ZJ configuration, ensuring all “5.9 zj obd2 wire” connections are secure and correctly placed for optimal performance of your newly swapped 5.9L engine.
