4/24020, 4/24021, 4/24090
Fault Code 4/24020, 4/24021, 4/24090Malfunction indicated
Problem in communication between the ETS and TC/ABS control units.
Fault symptom
The TCS CTRL lamp lights up and possibly also the ANTI LOCK lamp.
Test procedure
Note: If the car has been driven under abnormal conditions, e.g. on rollers, first check the 10 A fuse (red) in the ABS fuse holder.
If the ANTI LOCK lamp is on, always start fault tracing in the TC/ABS system. Testing and Inspection
1 With the ETS control unit connector unplugged, the TC/ABS control unit connector plugged in, and the ignition switch in the Drive position, use a BOB to check that the voltage applied to pin 32 of the ETS control unit connector is about 10 volts.
Also use the ISAT's PULSE function to check that no interference (pulses) is present on the lead connected to pin 32.
If interference occurs, disconnect both ETS and TC/ABS control units and check the BK/WH lead between pin 32 of the ETS control unit and pin 4 of the TC/ABS control unit for a short to earth +12 V.
2 With the ETS control unit connector plugged in, the TC/ABS control unit connect unplugged, and the ignition switch in the Drive position, use a BOB to check that the voltage applied to pin 24 of the TC/ABS control unit connector is about 10 V.
Also use the ISAT's PULSE function to check that no interference (pulses) occurs on the lead connected to pin 29.
If interference occurs, disconnect both ETS and TC/ABS control units and check the GN/WH lead between pin 29 of the ETS control unit and pin 24 of the TC/ABS control unit for a short to earth/+ 12 V.
3 If the above tests check out OK, clear the fault code and drive the car to see whether it is generated afresh. If it is, try fitting a TC/ABS control unit that is known to be OK
4 Try an ETS control unit which is known to be in proper working order.
Note: If the ignition switch is turned to the Start position too quickly, voltage differences in the switch may cause the ANTI LOCK and TCS CTRL lamps to light up, also generating fault code 44021.
If the fault code is only intermittent, there is no need to replace the ECU.