Jaguar XJ (X350). Manual — part 1361

Key Programming Using Two Programmed
Keys

1. To program additional PATS keys, a minimum of two valid keys must be available(if only
one key is available, it will be erased and reprogrammed with the new key).


2. Key programming using two programmed keys.

•

Insert the first valid key and turn to the run position for a maximum of five seconds,

then turn to off and remove the key.

•

Within ten seconds of removing the first key, insert the second valid key and turn to the

run position for a maximum of five seconds, then turn to off and remove the key.

•

To program the third (additional) key, insert the key and turn to the run position within

twenty seconds of removing the second key, allow the PATS LED to prove out for three
seconds to confirm storage of the additional key, then turn to off and remove the key.

•

This method can be used to store up to a maximum of 8 ignition keys.

Description and operation

Anti-Theft - Passive

Item Part Number

Description

1

—

Engine control module (ECM)

2

—

Passive anti-theft system (PATS) LED

3

—

Passive anti-theft system (PATS) transceiver

4

—

Instrument cluster

The passive anti-theft system (PATS) prevents the vehicle from being driven away by an
unauthorized persons. The PATS system consists of encrypted electronically coded keys, a
transceiver, instrument cluster (IC), and an engine control module (ECM). When the key is
inserted into the ignition barrel, the IC uses a decoding process via the transceiver to validate
the key transponder code. If the code matches one that is stored and the key is then turned to
the run position, the IC will perform a data transfer with the ECM, if valid the ECM will

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enable the fuel injectors, ignition coils, fuel pump drive and starter.

If the key is invalid the control function will send a theft status message to the ECM, which in
turn, will disable the vehicle from starting. If the correct key is used without a transponder or
used with a transponder with an incorrect code, the vehicle will be inhibited from starting.
This will prevent vehicle theft even if a duplicate key is cut.

A PATS indicator LED (located on the instrument panel) provides the driver with the status of
the PATS system. When the ignition is switched to the run position, the PATS indicator LED
will illuminate for three seconds and extinguish. If there is a fault with the PATS system after
60 seconds of continuous flashing, the PATS indicator LED will flash an error code.

Diagnosis and testing

Anti-Theft - Passive

The best method to confirm the correct operation of PATS is to check the LED (located in the center

of the instrument panel). The LED should illuminate solid for 3 seconds when the key is turned to the

run position and then extinguish. This validates the PATS functions (the key transponder matches the

key code stored, the challenge/response sequence between the instrument cluster (IC) and the

engine control module (ECM) was successful resulting in the ECM being enabled).

The ECM will disable the fuel injectors, ignition coils, fuel pump drive and starter if any of the

following conditions apply, a theft signal has been received from the IC (the key has not been

authenticated), a challenge code has been transmitted to the IC but no response code has been

received, a challenge code has been transmitted to the IC and an incorrect response received.

If any of the above cases apply, the ECM will log DTC P1260. This DTC is further defined by sub-codes.

The sub-codes are accessed through mode 12 (freeze frame data). Additionally the IC will log DTC's if

the failure was a result of the key read.

Engine fails to crank

If a PATS fault is detected, the LED will flash for 60 seconds at 4Hz with a 50% duty cycle. At the end

of this period, the LED will flash a 2 digit code, this code is repeated 10 times. The meaning of this

code along with the frequency of flashing is given in the accompanying table (as a general rule a fault

code of 16 or less will cause the vehicle not to crank. Additionally, the Jaguar Approved Diagnostic

System should be used to check the DTC stored in the IC.

The most regular occurrence for failing to crank is due to the park and neutral switches (gearshift not

in park or neutral). The start circuit is as follows, low side of relay coil (Switched directly from the

instrument cluster, if conditions correct), high side of relay of coil (from ignition start position

through gearbox rotary start switches to relay).

Another likely cause maybe the CAN network is malfunctioning, (the CAN circuit is open/short). This

means that the IC and ECM would be unable to communicate resulting in no challenge being

performed to enable the ECM.

On US manual vehicles the addition of a clutch switch has been included in the starting circuit, this

switch takes place of the park/neutral switch (auto transmission). The switch activates at end of

travel (clutch fully depressed).

Engine cranks but will not start

If the engine is cranking it means that the ECM is enabled with respect to the PATS. If PATS was

disabled the ECM would not engage the starter. This could be confirmed by verifying the PATS LED

prove out (illuminated solid for 3 seconds) or by reading DTC's from the IC and ECM. In this case, the

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