1994 JAGUAR XJ6 automatic transmission

Powertrain Automatic Transmission (V12)
Traction Control Active Input - PI 782
Function:
ABS signal monitor.
Connections: TCM Connector
CCO48/023 FCOO7/041
Connector Connector
FCOO5/025 LHD LSOO3/017 LHD
FCOO6/040 RHD RS003/00D RHD Connector
FCO57/008
ABS / TC CM
LSO27/003 LHD
RS027/003 RHD
Possible
causes:
8 Faulty harness wiring / connection.
8 Faulty signal from ABS / TC CM.
Effects:
8 No 'shift inhibit' during traction control.
Remedy:
8 Repair or renew harness / connector. - Examine ABS / TC CM fault diagnosis (refer to EDM Section 14). Connector
FCO57/002
P2:
1
Traction
control active -fault code PI782
-
'03
14
JE6 1751
Issue 1 August 1994 X300 EDM 23

I' Automatic Transmission (V12) Powertrain
PI Harness
Pl063/00 1
Throttle Position Signal Fault - P1791
Function:
Throttle position signal monitor.
Connections: TCM
CC04810 1 1
Possible causes:
Faulty harness wiring 1 connection.
Faulty ECM signal.
Effects:
9 MIL illuminated.
Fixed shift points, giving harsh shifts.
Remedy:
Repair or renew harness 1 connector.
Examine ECM fault diagnosis (refer to EDM, Section 5.2).
ECM
PI 104/004
P' 1
1
Throttle position -fault code P1791
7-1 GN
Fia. 1
W4
8
J86 ~ 1752
X300 EDM Issue 1 August 1994 24

Automatic Transmission (V12) - Powertrain
System Voltage Malfunction - P1794
Function:
Battery voltage monitor.
Possible causes:
. Faulty harness wiring /connection.
. Blown fuses.
Effects:
. MIL illuminated.
. Second gear selected permanently ie ‘Limp Home’ mode.
Remedy:
Repair or renew harness I connector.
. Examine fuse F14 and F5 in LH and RH heelboard fuse-boxes respectively.
. Renew (if necessary) after determining cause of rupture.
P5 5
P53
1
I -3---+-2 YR
System supply voltage -fault code PI794
J86 - 1 753 Fig. 1
- Note: * +12V present only when ignition switched ON
X300 EDM ~.
25 Issue 1 August 1994

I:.
Powertrain Automatic Transmission (V12) w
Kickdown Switch System - P1796
Function:
Switch operation monitor.
Connection: TCM Connector
CCO48/024 FCOO7/009
Possible causes:
8 Faulty harness wiring /connection.
8 Faulty switch (or switch adjustment).
Effects:
No kickdown facility.
Remedy:
8 Repair or renew harness / connector.
Re-adjust or renew switch. Switch
in
CA074/001 RHD
FCO19/001 LHD
Ground
CA074/002 RHD
FCO 191002 LH D
Kickdown switch -fault code PI796
Fig. 1

E I ect r ical IT
SPEED CONTROL
System Description
0 15.3 15.3.1
The speed control system provides an automatic cruise facility, allowing a constant speed to be maintained without
accelerator pedal operation. The system comprises the following components:
0 Electronic control unit
0 Vacuum dump valve
0 Control valve
0 Vacuum pump
0 Mechanical throttle linkage and bellows
0 Selection switch
0 Brake and clutch pedal switches
On selection of speed control, via the switches mounted on the driver's side fascia, the vacuum dump valve, pump and
control valve will energize, creating
a partial vacuum in the bellows assembly. The bellows assembly acts upon the
throttle linkage to adjust throttle position, maintaining vehicle speed at the value when control is selected.
Speed control is determined by the Speed Control Control Module
(SC CM) which monitors a speed signal delivered
from the instrument pack (initially from the ABS rear LH wheel speed sensor) to determine vehicle speed.
Speedcontrol isdisabled, returning control tothedriver,
byoperationofthevacuumdumpvalve,ifanyofthefollowing situations occur: 0
0 Braking
0 Clutch operation (3.2 / 4.0 litre manual transmission vehicles only)
o Drive de-select ie P, N or R (automatic transmissions only, both electronic and hydraulic)
0 Traction control system (where fitted) in operation
0 Rapid speed reduction without braking input, ie double brake switch failure
0 Actual speed drop to 3/4 of cruise setting (eg when towing excessive loads under adverse conditions)
0 Vehicle speeds below w 25 mph
0 Ignition OFF
0 De-selection at switch controls
15.3.2 COMPONENT DESCRlPTlO NS
15.3.2.1 Electronic Control Module
The Speed Control Control Module (SC CM), located behind the fascia, adjacent to the steering column, provides sys- tem control and an interface to external input signals from the instrument pack, gear selector module, traction control
system, control switches, and foot pedal switches. The set speed value is retained in SC CM memory and continuously
compared to actual vehicle speed. Adjustments are made, as necessary, to maintain set speed by control of the vac- uum pump and control valve. Connections to the SC CM are listed in the table on page 3.
X300 EDM 15.3 - 1 Issue 1 August 1994

0 15.3.3 SYSTEM FLOW CHARTS
Systematic fault diagnosis of the speed control system cannot be accurately achieved by attempting to simulate actual
driving conditions. The system can only be reliably and safely tested using Jaguar Diagnostic Equipment.
15.3.4 DIAGNOSTIC SUB-ROUTINES
The following information details possible fault conditions, causes and remedies.
components are covered in Pin-point Tests. Detail test procedures
for
Fault: System inoperative
Possible causes:
1. Fuse FIO (LH 'A' post base fuse-box) blown.
2. Pneumatic circuit fault (ie vacuum leak)
3. Brake switch fault.
4. Clutch switch or link fault. Gear position input fault (automatic transmission only).
5. Harness wiring or connector faulty.
6. Set switch faulty.
7 Paddle switch faulty
8. Traction control input high.
9. Road speed input missing.
10 Dump valve failure.
11 Vacuum pump 1 control valve unit failure.
Remedy: 1. Examine fuse F10, if blown determine reason for failure and renew.
2. Examine all pipework, connections and components for damage or
disconnections, repair
or renew as necessary.
3. Check brake switch operation, renew if necessary.
4. Check clutch switch operation (manual transmission) or link connection I position input
(automatic transmission), renew if necessary.
5. Examine harness wiring. Examine connectors for corroded, damaged or distorted pins.
6. Check set switch operation and wiring, renew if necessary.
7. Check paddle switch operation and wiring, renew if necessary.
8. Examine harness wiring between SC CM and ABS / TC CM, check ABS /TC CM fault
diagnosis.
9. Examine harness wiring between SC CM and instrument pack, check pack fault diagnosis.
10 Renew faulty valve.
11 Renew faulty unit
0
Fault:
Cause:
1. Clutch pedal switch or harness failure.
Clutch pedal operation does not disable system
1. Remedy: Check switch operation and wiring connections. Repair or renew switch / wiring
as necessary.
Fault:
Cause:
1, Faulty signal from gear selection module.
Remedy: 1. Examine transmission fault diagnosis.
Neutral gear selection does not disable system (automatic transmissions only)
2.
2.
Harness wiring or connector fault
Examine harness between gear selection module and SC
CM pin 18.
X300 EDM 15.3 - 5 Issue 1 August 1994

15.3.5 PIN-POINT TESTS
The following tests give detailed information on component fault diagnosis.
1. Power supply
a. Check fuse FIO in LH 'A' post base fuse-box is intact.
b. Unplug harness connector from SCCM and check for battery supply voltage to ground, at pins 1 and 2
with ignition on. If supply is not recorded on either pin switch off ignition and check harness wiring
continuity from LH
'A' post base fuse-box to splice FCS16.
If supply is recorded at pin 1 only check brake and clutch (where fitted) switch contacts (closed when
pedals not operated). For vehicles with automatic transmission ensure clutch pedal switch link is
correctly fitted. Examine harness wiring and check continuity between pin
2 and splice FCS16.
If supply is recorded at pin 2 only examine harness wiring and check continuity from pin 1 to splice
FCS
16.
c.
d.
m
P1I
1
k wv I wu I
I-------
*+12V Present Only When Ignition ON
1. Speed Control Control Module (SC CM) 7. Dump Valve
2. Clutch Switch / Link 8. Control Valve / Pump Unit
3. Brake Switch
9. Gear Position Module 4. LH 'A' Post Base Fuse-box 10. ABS Control Module 5. Switch Pack 11. Instrument Pack
6. Column Switchgear Dimmer
Fig. 1 Speed Control Power Supply
Issue 1 August 1994 X300 EDM 15.3 - 7