1998 JAGUAR X308 Transmission Control Module

In the event of a system fault, the TCM will adopt 'limp home' mode.
Electrical control
Refer to Section 307-01B.
Transmission Control Components
Transmission Control Module (TCM)
The TCM controls the transmission internal components thus determining gear selection and shift pattern.

The TCM is located in the same housing as the engine control module (ECM) and is accessed in the same manner. With the
two connectors unplugged the TCM may be withdrawn, complete with mounting bracket. The mounting bracket is secured to
the TCM by 2 locknuts.
Operation
CAUTION: Disconnection of OTHER contro l module connectors and / or the vehicle battery, may introduce fault codes
(DTCs). Following rectification and reconnection, ensu re that no induced codes exist in the TCM memory.
The TCM processes input and output in both analogue and di gital form which may be summarized in four categories:
Input Signals
Gear selector position (Dual Linear Switch x 4 inputs see 307.05) Transmission oil temperature Kickdown Speed sensor #1 Speed sensor #2 Mode switch

and/or increased performance as appropriate.
Serial Communications Interfaces
Controller Area Network (CAN)
The TCM is an integral part of the CAN system which facilita tes the interchange of real-time data between control modules
and sensors; refer to 303-14 fo r a full description of CAN.
Transmission Pressure Regulators and Shift Solenoids Circuit Diagram

ItemPart NumberDescription
1—Transmission oil temperature sensor
2—Switch
3—Shift solenoid 1 <-> 2, 4 <-> 5
4—Shift solenoid 2 <-> 3

Speed Sensor / TCM Circuit Diagram

Connector Pins Identification
Connector Pin Identity Chart for EM061
5—Shift solenoid 3 <-> 4
6—TCC pressure regulator
7—Modulation pressure regulator
8—Shift pressure regulator
9—Engine compartment fuse box
10—Transmission control module
11—Transmission
ItemPart NumberDescription
1—n2 speed sensor
2—n3 speed sensor
3—Engine compartment fuse box
4—Transmission control module
5—Transmission

Automatic Transmission/Transaxle - 4.0L SC V8 - AJ26 - Diagnostic
Strategy
Diagnosis and Testing
Symptom Chart
Symptom Chart
Special Tool(s)

Digital multimeter

Generic scantool
SymptomPossible SourcesAction
DTC P0740 Torque converter clutch system
electricalHarness fault
Connector pins(s) bent , loose or corroded
*
*GO to Pinpoint Test A
*
DTC P0740 Torque converter clutch system stuck
onTorque converter clutch stuck on
*GO to Pinpoint Test B
*
DTC P1744 Torque converter clutch system stuck
offTorque converter clutch stuck off
*GO to Pinpoint Test B
*
DTC P0702 Transmission control system electricalHarness fault
High side switch (FET) fault
Connector pins(s) bent , loose or corroded
*
*
*GO to Pinpoint Test C
or D
*
DTC P0753 Shift solenoid A electricalHarness fault
Solenoid open circuit
Solenoid short
Connector pins(s) bent
, loose or corroded
*
*
*
*GO to Pinpoint Test C *
DTC P0758 Shift solenoid B electricalHarness fault
Solenoid open circuit
Solenoid short
Connector pins(s) bent
, loose or corroded
*
*
*
*GO to Pinpoint Test C *
DTC P0763 Shift solenoid C electricalHarness fault
Solenoid open circuit
Solenoid short
Connector pins(s) bent
, loose or corroded
*
*
*
*GO to Pinpoint Test C *
DTC P0748 Pressure control solenoid electricalHarness fault
Pressure regulator open circuit
Pressure regulator short
Connector pins(s) bent
, loose or corroded
*
*
*
*GO to Pinpoint Test D *
DTC P1748 Pressure control solenoid B electricalHarness fault
Pressure regulator open circuit
Pressure regulator short
Connector pins(s) bent
, loose or corroded
*
*
*
*GO to Pinpoint Test D *
DTC P0702 Transmission control system electricalHarness fault
Speed sensor voltage supply out of
tolerance Connector pins(s) bent , loose or corroded
*
*
*GO to Pinpoint Test E
*
DTC P0715 Input / turbine speed sensor circuit
malfunctionSpeed sensor n2 or supply open circuit
Speed sensor n3
Harness fault
Connector pins(s) bent , loose or corroded
*
*
*
*GO to Pinpoint Test F
*
DTC P1601 Internal control module computer errorFaulty TCM
*GO to Pinpoint Test G *

Transmission/Transaxle Cooling - 4.0L NA V8 - AJ27/3.2L NA V8 - AJ26 -
Transmission Cooling
Description and Operation
The transmission fluid cooling system maintains fluid temperature within specified limits.

Parts List
Component Descriptions
The transmission fluid pipes:
Transfer fluid from the transmission to the cooler under the action of the hydraulic system pump. Return the cooled fluid from th e cooler to the transmission.
The transmission fluid cooler:
Is a plate type made from aluminum. Is mounted in the engi ne cooling radiator right-hand end tank.
Overheating Protection
If the engine coolant or transm ission fluid temperatures exceed their predefined limits, th e transmission control module locks
the torque converter clutch. By reducing slip, this minimises th e amount of heat transferred to the engine cooling system from
the transmission fluid.

ItemPart NumberDescription
1—Fluid pipe, oil FROM cooler
2—Fluid pipe, oil TO cooler

Transmission/Transaxle Cooling - 4.0L SC V8 - AJ26 - Transmission
Cooling
Description and Operation
The transmission fluid cooling system maintains the fluid temperature within specified limits. The cooling element is located
in the engine cooling radiator LH end tank.
Fluid is circulated, under pressure, by the transmission pump to the cooler.
General Layout

Overheating Protection
If the engine coolant or transmission fluid temperatures exceed their predefined limits, the transmission control module
locks the torque converter clutch . By reducing slip, this minimises the amount of heat transferred to the engine cooling
system from the transmission fluid.

Automatic Transmission/Transaxle External Controls - 4.0L NA V8 -
AJ27/3.2L NA V8 - AJ26 - External Controls
Description and Operation
Introduction
Driver gearshift control is effected by:
The gear shift lever. The accelerator pedal position. The kickdown switch (where fitted). The performance mode pushbutton.
Driver's Selector Module ('J' Gate)

The gear selector lever:
Has seven positions: Park, Reverse, Neutral, Drive, Fourth, Third and Second. Operates the transmission selector shaft and rotary switch, in all positions (except Drive-to-fourth) by means of a
Bowden cable.
Passes driver gearshift requests to the transm ission control module via the rotary switch.
ItemPart NumberDescription
1—Gear selector lever
2—Drive-to-fourth switch connector
3—Neutral position switch connector
4—Park position switch connector
5—Gear selector illumination module
6—Gear selector interlock solenoid
7—Security system Active LED

The Drive-to-fourth switch:
Detects when the gear selector lever is moved from Drive to Fourth. Is hard-wired to the transmission control module.
The Neutral position switch:
Is hard-wired to the body processor module. Detects when the gear selector lever is moved to the Neutral position.
The Park position switch:
Is hard-wired to the body processor module. Detects when the gear selector leve r is moved to the Park position.
The gear selector module:
Provides illumination of the gear sele ctor surround, which is dimmable via a CA N signal from the instrument cluster. Provides red illumination, on the gear selector surround, of the gear selected, by CAN signals from the instrument
cluster.
Illuminates the security system Active LED on the gear se lector surround, in response to an input from the body
processor module.
Is connected to the fascia harness via a 12-way connector. Refer to Connec tor Pins Identification, 307-01A.
The gear selector interlock solenoid:
Prevents the gear selector lever from be ing moved from the Park position, unless th e ignition switch is in position II,
and the brake pedal is depressed.
Is controlled by an input from the body processor module.
The seven gear selector positions are:
P : The transmission is mechanically locked (starting available). R : Reverse gear. N : No power to the rear wh eels (starting available). D : All 5 forward gears available. 4 : Upshift to 4th gear only. 3 : Upshift to 3rd gear only. 2 : Upshift to 2nd gear only.
Performance Mode Pushbutton

The performance mode pushbutton:
Is mounted on the gear selector surround. Selects Normal or Sport mode when pressed by the driver. Is illuminated when Sport mode is selected.