DTC 124

DH. DTC 1-2-4
1-2-4 Short-circuit to ground in driving mode selector

Principle of operation

The driving mode selector enables the driver to select the desired driving mode. Two signal leads, MS1 and MS2, and a ground lead are connected to the three buttons. The W, E and S modes are selected by grounding either the first, the second or both signal leads, whereupon the TCM adopts the appropriate gear selection program. Note that MS1 and MS2 are grounded simultaneously only while the W button is depressed.

Fault description

MS1 and MS2, which may be high or low, are the signals which determine the driving mode used by the system. In the case of this fault, MS1 and MS2 remain constantly low and the system runs continuously in Mode E (Economy). The MIL is not lit.

The fault must be present for at least 30 seconds for the DTC to be recorded. Thus, the DTC can be recorded if the W button sticks or is kept depressed for a prolonged period.

Troubleshooting should indicate if the short-circuit is in the lead to MS1 or MS2, or if the driving mode selector or TCM is faulty.





Principle of operation

The circuit consists of the TCM, three connectors, and the driving mode selector.





1
Testing driving mode selector in test mode 2

Test driving mode selector in all positions in test mode 2. Displaying & Reading Trouble Codes

If response codes 3-2-4, 2-4-4 and 3-1-4 are correct, fault is occurring only intermittently under particular conditions, making it considerably more difficult to locate.





2
Measuring driving mode selector voltage

- Switch off ignition.
- Connect break-out box between TCM and wiring.
- Switch on ignition.





Measure voltages as indicated in table.

Note!
In measurements including W mode, W button must be kept depressed throughout measurement. DTC 1-2-4 will be recorded if button is held depressed for longer than 30 seconds.

- If readings are as specified in table and LEDs on selector light when appropriate button is pressed, driving mode selector and wiring are OK.

In that case, DTC is due to intermittent fault. Proceed to next step.





3
Measuring driving mode selector voltage

- Switch off ignition.
- Remove driving mode selector from center console.
- Connect ohmmeter between driving mode selector connector terminals as indicated in table (terminal 1= MS2, terminal 2 = MS1, terminal 3 = ground).





If readings are incorrect as per table, driving mode selector is faulty. Replace selector as per Transmission Position Switch/sensor. Service and Repair

If readings are correct as per table but fault is present as in step 2 above, check connections and wiring as described in Testing and Inspection. Component Tests and General Diagnostics

4
Conclusions

- If LEDs do not light, connection of driving mode selector is probably poor. Check connectors and ground lead as described in Testing and Inspection. Component Tests and General Diagnostics

- If fault persists although LEDs light, leads MS1 and MS2 are probably shorted, check connections and wiring as described in Testing and Inspection. Component Tests and General Diagnostics

- If only one LED lights, driving mode selector is faulty.

After test driving as per Testing and Inspection, Flow of Diagnosis. Diagnostic Procedures

- If control system not does change modes although above readings are correct, fault is in TCM.

If driving mode selector is faulty, replace as per Transmission Position Switch/sensor. Service and Repair