JAGUAR XJ6 1994 2.G Electrical Diagnostic Manual

rl Electrical
15.2.8.12
1. Measurevoltage at pack pin 40 (LH) and 41 (RH), 48-wayconnector, Ovolts indicatessignal low ie lamp ON. Avaiue of 12V at pin 24 indicate lamp off.
Direction Indicator Tell Tales (Active Low)
1. Instrument pack
9. Body processor unit
J86.1901
Fig. 1 Direction Indicators
Issue 1 August 1994 15.2 - 18 X300 EDM

15.2.8.13
2. Checkvoltage at pin 9,48-way connector. A value of approximately 12V indicates alternator signal healthy, 0 volts
indicates fault condition.
Generator IND Voltage Indicator (Active Low)
1. Check for battery voltage (13 f 2.5V) between pins 2 and 4 of pack 24-way connector.
(4a wnv) P9
1. Instrument pack
13. Generator
J86-1845
Fig. 1 General IND Voltage Indication I
X300 EDM 15.2 - 19 Issue 1 August 1994

rl E I ect r ical
15.2.8.14
1. Check washer fluid in reservoir is within normal level limits and top up if necessary.
2. Check continuity across sensor pins, short circuit indicates acceptable fluid level, open circuit indicates low fluid
level.
3. Check voltage at pin
13,48-way connector. A value of approximately OV indicates signal healthy ie lamp off, 12
volts indicates fault condition ie lamp on.
Washer Fluid level Indicator (Active High)
1. Instrument pack
14. Washer fluid level switch
JE-1846
Fig. 1 Washer Fluid Low Level Indication

15.2.8.15
2. Check continuity across sensor pins, short circuit indicates acceptable fluid level, open circuit indicates low fluid
level.
3. Check voltage at pin 37, 48-way connector. A value of approximately OV indicates signal healthy ie lamp off, 12 volts indicates fault condition ie lamp on.
Engine Coolant level Indicator (Active High)
1. Check fluid in coolant reservoir is within normal level limits and top up if necessary.
(48 WAV P3i
1
1. Instrument pack
15. Coolant level sensor
JW-1847
Fig. 2 Coolant Low Level Indication
X300 EDM 15.2 - 21 Issue 1 August 1994

rl E I ect r ical
15.2.8.16
1. Check fluid in fluid reservoir is within normal level limits and top up if necessary.
2. Check continuity across sensor pins, short circuit indicates acceptable fluid level, open circuit indicates low fluid level.
3. Check voltage at pin 10,48-way connector. A value of approximately OV indicates signal healthy ie lamp off, 12
volts indicates fault condition ie lamp on.
Brake Fluid level Indicator not illuminated when fluid level low (Active High)
(48 WAYl P10
1
1. Instrument pack
16. Brake
fluid level indicator
J86-1848
Fia.1 Brake Fluid Low Level Indication
0
0
0
0
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15.2.8.17 General Bulb Failure lndicator (Active Low)
1. Check all monitored bulbs are operating correctly and have clean contacts.
2.
3.
4.
When bulb failure lamp is illuminated and direction indicator tell tales flash at double the normal rate suspect a
fault in the direction indicator circuitry or bulbs.
Check
all lighting modules (LH front, RH front and rear) are correctly connected. Check harness continuity from
modules to BPU.
If indicator tell tales do not flash at double normal rate check wiring harness continuity between pin 43 (48-way
connector) and Logic Control Module (LCM) harness connections 8 (LH and RH side) and 6 (rear).
(48 WAY) P4
1
1. Instrument pack
10. Lighting module (LH front) 11. Lighting module (RH front)
12. Lighting module (rear)
J86-1844
Fig. 2 General Bulb Failure Indication
X300 EDM 15.2 - 23 Issue 1 August 1994

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

Electrical rl
1. Speed control switches 5. Speed control control module (SC CM)
2. Throttle linkage and bellows 6. Brake switches 3. Vacuum dump valve 7. Clutch switch (where fitted)
4. Vacuum pump and control valve unit
Fig.
1 Speed Control System Component Locations

Electrical D ~
Ignition
+ve feed
Ignition +ve switched supply output I 01 03
06 Speed signal input
09 Traction Control input
10 Control valve control output
11 Ground
12 Ignition +ve input
14
15 ~
Stop
lamp input
17
1 Control switches input
18
j Gear select input
' Dump valve control output ~
20 I Vacuum
pump control output
15.3.2.2 Speed Control Module Pins
1 Pin No 1 Description I Comment
0
Feed to vacuum pump /control valve unit and
dump valve
via brake and clutch switches (or link)
0
0
1 10
A
11 'I n n 01 *O
I" " 1:
J86 1879
Fig. 1 Speed Control Module multi-pin Connector
15.3.2.3 Vacuum Pump /Control Valve Unit
The vacuum pump / control valve unit is located under the hood, behind the LH headlamp. When adjustment of the
throttle position is required, the pump and valve are 'pulsed' on/off by the SC CM to achieve the required vacuum and
hence vehicle speed.
15.3.2.4 Pressure Release Valve
The pressure release (or dump) valve is located adjacent to the vacuum pump /control valve module and opens, vent- ing system air pressure to atmosphere, when speed control is disabled.
X300 EDM 15.3 - 3 Issue 1 August 1994