(NA) Diagnostic Trouble Codes (DTC) 1-1-2 and 1-2-2

NA. 1-1-2 and 1-2-2 Vehicle Speed Signal Incorrect

If a safety disengagement has occurred because of an incorrect speed signal, DTC 1-1-2 will be posted. This DTC will be posted only if the control module sensed a correct signal some time during the test drive, i.e. not during stationary interruptions.

Safety disengagement does not necessarily imply a problem with the cruise control system. Safety disengagement occurs when the cruise control is inappropriately engaged during abnormal speed changes, for example rapid acceleration (wheel spin) or rapid deceleration (wheel locking). The speed can drop to less than 75% of the programmed speed on steep inclines where the engine is unable to maintain constant speed.


Abnormal speed signals when a safety disengagement has not occurred during the test drive there is intermittent interference in the speed signal to the control module. The interference can be caused by accessories and systems connected to the same speed signal as the cruise control or the same ground point as the speedometer. Interference can also occur if the control module and speedometer are not connected to the same ground point.

DTC Information 1-2-2

This DTC is posted when the ignition is turned on and remains until the car speed has been over 22 mph for at least 15 seconds. If the code is still posted after a test drive over 22 mph the control module is not receiving a speed signal. Fault tracing begins with NA1.


NA1. Testing Control Module Ground Connection






Ignition off.
Disconnect control module.
Using an ohmmeter, measure the resistance between control module socket terminal 3B and ground.
The ohmmeter should display about 0 ohm.

If reading is OK:
Power supply test NA2.

If reading is not OK:
Check cable from control module socket terminal 3B and ground for breaks according to QA2. (Q) Other Electrical Fault Tracing


NA2. Power Supply Test






Ignition off.
Disconnect control module.
Ignition on.
Using a voltmeter, measure the voltage between terminals 1B and 3B on the control module socket. Voltmeter should display battery voltage.

If reading is OK:
Speedometer test NA4.

If reading is not OK:
Fuse check NA3.


NA3. Fuse Check






Check that fuse 19 in the central electronics module (inside the car) is intact.

If fuse is intact:
Check the cable between fuse 19 and control module terminal 1B for breaks, according to QA2.

If fuse is blown:
Check cable between: fuse 19 and switch terminal 2, fuse 19 and control module terminal 1B, switch terminal 1 and brake valve.

Automatic transmission: brake valve and control module terminal 9E, manual transmission: brake valve and clutch valve, manual transmission: clutch valve and control module terminal 9E.

Switch terminal 3 and control module terminal 6E, switch terminal 4 and control module terminal 8E, switch terminal 5 and control module terminal 4E for short circuits to ground according to QA3.


NA4. Speedometer Test






Check whether speedometer works while driving.

If speedometer works while driving:
Speed signal test NA5.

If speedometer does not work while driving:
Fault trace speedometer.


NA5. Speed Signal Test






Ignition off.
Disconnect control module.
Lift car so that rear wheels are free.
Connect a voltmeter between control module socket terminal SB and ground. Spin rear wheels slowly.
Voltmeter should oscillate between battery voltage and about 1.5 volts when the wheels are spun.

If the readings are OK:
The DTC is caused by poor contact in the connectors. Service the control module socket terminal SB, the 12/22-pin connector at the parking brake bracket (34/19) terminal 12 and 13 and the multi connector at the left A-post (A1/E) terminal 13 for contact resistance and oxidation, according to QA6, and for loose connection, according to QA5.

If voltmeter displays constant battery voltage:
Check the cable between combined instrument terminal D and control module socket terminal SB for short circuit to supply, according to QA4.

If voltmeter displays constant battery voltage minus 2 volts:
Check cable from combined instrument terminal D and control module socket terminal SB for breaks, according to QA2.

If voltmeter displays constant 0 volts:
Check the cable between combined instrument terminal D and control module socket SB for short circuit to ground, according to QA3.