Jaguar XJ (X350). Manual — part 1164

two return springs to guarantee the accelerator returns to the zero position when the pedal is
released. Whilst comparison checks are carried out on the accelerator pedal for rational
values, communications within the ECM are monitored for rational values and responses.

The ECM then provides an output, based on the accelerator pedal position, which drives a DC
motor which positions the throttle blade at the requested angle. The throttle blade position is
monitored by two sensors for rational value.

The acceleration control system has the necessary safety features to monitor the correct
operation of all the components. Depending on the failure state, the acceleration control
system can be put in appropriate safe state, from restricting the RPM to limphome mode.

Diagnosis and testing

Acceleration Control

1 . Verify the customer concern by operating the system.

2 . Visually inspect for obvious signs of mechanical or electrical damage.

3 . If an obvious cause for an observed or reported concern is found, correct the cause (if possible)

before proceeding to the next step.

4 . If the concern is not visually evident, use a fault code reader to retreive fault codes before

proceeding to the Symptom Chart.

DTC P1240, P1241, P1242

Possible Source(s):

Accelerator pedal power supply circuit out of range

Action(s) to take:

GO to Pinpoint Test A.

DTC P1122, P1123, P1215, P1216, P1344

Possible Source(s):

Accelerator pedal demand sensor output circuit out of range

Action(s) to take:

GO to Pinpoint Test B.

DTC P0121, P0122, P0123

Possible Source(s):

Throttle position sensor circuit out of range

Action(s) to take:

GO to Pinpoint Test C.

DTC P1251, P1658, P1631,

P1657

Possible Source(s):

Throttle motor relay failure

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Action(s) to take:

GO to Pinpoint Test D.

DTC P1243

Possible Source(s):

Accelerator pedal demand sensor ground; open circuit

Action(s) to take:

GO to Pinpoint Test E.

DTC P1611, P1633

Possible Source(s):

Engine control module (ECM) failure

Action(s) to take:

INSTALL a new ECM. For additional information, refer to <<303-14>>.

DTC P1254, P1250

Possible Source(s):

Throttle limp home spring malfunction.

Action(s) to take:

INSTALL a new throttle body. For additional information refer to <<303-14>>.

PINPOINT TEST G240070p1 : DTC
P1240, P1241, P1242

G240070t1 : CHECK THE POWER SUPPLY TO THE ACCELERATOR PEDAL
DEMAND SENSOR

1. TURN the ignition switch to the RUN position. 2. Measure the voltage between electrical connector

CA88 pin 5 (Y) and ground. 3. Measure the voltage between electrical connector CA88 pin 2 (Y) and

ground.

Is the voltage less than 4.5 volts?

-> Yes

GO to Pinpoint Test G240070t2.

.

-> No

DIAGNOSE the electronic engine control system. For additional information, refer to <<303-14>>.

G240070t2 : CHECK CONTINUITY OF THE ACCELERATOR PEDAL DEMAND
SENSOR POWER SUPPLY CIRCUIT

1. Turn the ignition switch to the OFF position. 2. Disconnect the ECM electrical connector PI 1 and

the accelerator pedal electrical connector CA 88. 3. Measure the resistance between PI 1 pin 13 (Y)

and CA88 pin 5 (Y). 4. Measure the resistance between PI 1 pin 12 (OY) and CA88 pin 2 (OY).

Is the resistance less than 5 ohms?

-> Yes

GO to Pinpoint Test G240070t3.

.

-> No

REPAIR the power supply circuit from the ECM to the accelerator pedal. CLEAR the DTC. TEST the

system for normal operation.

G240070t3 : CHECK THE ACCELERATOR PEDAL DEMAND SENSOR POWER
SUPPLY FOR A SHORT CIRCUIT TO GROUND

1. Measure the resistance between CA88 pin 5 (Y) and ground. 2. Measure the resistance between

CA88 pin 2 (OY) and ground.

Is the resistance greater than 10,000 ohms?

-> Yes

DIAGNOSE the electronic engine control system. For additional information, refer to <<303-14>>.

-> No

REPAIR the power supply circuit from the ECM to the accelerator pedal. CLEAR the DTC. TEST the

system for normal operation.

PINPOINT TEST G240070p2 : DTC
P1122, P1123, P1215, P1216, P1344

G240070t4 : CHECK THE ACCELERATOR PEDAL DEMAND SENSOR OUTPUT

1. Turn the ignition switch to the RUN position. 2. Measure the voltage between electrical connector

CA88 pin 1 (O) and ground with the accelerator pedal released and with the accelerator pedal at full

throttle. 3. Measure the voltage between electrical connector CA88 pin 4 (B) and ground with the

accelerator pedal released and with the accelerator pedal at full throttle.

Does the voltage vary between 0.75 volts and 3.5 volts?

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