Central Timer Module Diagnostics
Diagnostic Mode
The diagnostic mode is used to test the CTM and its associated connections while the CTM is in the vehicle. The technician can retrieve and clear internally stored trouble codes and also individually test each of the CTM inputs while in this mode. Normal CTM functions are disabled while in this mode. Wiper functions are also disabled while in this mode. However, the wiper motor output is operated by the washer switch input during the Input Test to allow testing of the wiper motor status switch input.
Entering/Exiting Diagnostic Mode
The diagnostic mode is entered by grounding the black one-pin diagnostic connector. The connector is clipped to the I/P reinforcement to the right of the steering column bend bracket and in front of the black relay box #1.
The diagnostic mode is exited (returned to normal operation) immediately upon removal of the ground on the diagnostic input.
Retrieving Diagnostic Trouble Codes (DTCs)
The diagnostic mode consists of the following three steps:
1. Tone and/or Door Ajar Lamp Test
2. Trouble Code Test
3. Input Test
Erasing Diagnostic Trouble Codes (DTCs)
Trouble codes are erased when either:
1. The ignition has been moved to START position at any time during diagnostic mode.
2. Power is removed from CTM.. 7BUO23 002
1. Tone and Door Ajar Lamp Test
NOTE:
^ Step 1 is run immediately upon entry into the diagnostic mode.
When the diagnostic mode is first entered (by grouping the test pin connector) and the key is ON, the CTM will generate a tone and/or light the door ajar lamp for three (3) seconds. The tone sounds different than the normal warning chime.
If the key is in RUN or ACCY use the following table if the diagnostic mode can not be entered.
After the three second test is completed, the tone will stop and the door ajar lamp will go out and the CTM will pause for one second. Next, proceed to Step 2 or Step 3.
NOTE:
^ On some vehicles, the door ajar lamp will not light during this test. This is due to software differences in the CTM. If the door ajar lamp does not light, but comes on when the door is open or during the input test, then the system is functioning properly.
2. Trouble Code Test
NOTE:
^ Step 2 is run with the key in the ignition. To output trouble codes with the key out of the ignition, do not remove the test pin connector ground. If the ground is removed, the CTM will switch from the diagnostic mode to normal operation.
NOTE:
^ This diagnostic mode is used to test the CTM and associated connections while the CTM is in the vehicle. While in this mode, the technician can retrieve and clear the internally stored trouble codes and also individually test each of the CTMs inputs. Normal CTM operation is disabled while in the diagnostic mode.
NOTE:
^ When the CTM is in the normal mode of operation, it is continually monitoring itself. When a fault occurs, it is recorded. The trouble code output mode shows these codes, if any, to the technician by flashing the door ajar lamp and/or simultaneously sounding the chime in a certain order. These may be used to help diagnose potential intermittent failures.
Displaying Trouble Codes
Trouble codes are output to the operator through flashing of the door ajar lamp and/or the sounding of a chime. Each code is represented by a two-digit number. The high digit is output first followed by a one second pause followed by the second digit. Each two-digit code is separated by a three (3) second pause. Each digit is made up of one to five one-second flashes. The codes will be continually output until the ground is removed and the CTM switches to normal operation.
NOTE:
^ On some vehicles, the door ajar lamp will not light during this test. This is due to software changes to the CTM. If the door ajar lamp does not light, but comes on when the door is open or during the test, then the system is functioning properly.
For example, if the CTM has stored codes 22 and 23, the codes will be output:
(22) Two one-second flashes and/or tones -- one-second pause -- two one-second flashes and tones-- three-second pause.
(23) Two one-second flashes and/or tones -- one-second pause -- three one-second flashes and tones.
NOTE:
^ The entire set of stored trouble codes will be stored indefinitely until either the input test mode is entered or the ground is removed from the diagnostic input. The following table shows all of the possible trouble codes.
3. Input Test
NOTE:
^ Step 3 is run with the key in the ignition.
The input test allows an operator to individually test the CTM inputs. It is entered when the operator puts the key into the ignition. The input may be cycled in any order. As an input is toggled on or off, the door ajar lamp and tone outputs will be activated for one second for confirmation. At any time, if the key is removed from the ignition assembly, the trouble code output will be reentered.
NOTE:
^ When testing the interval windshield wipers, turning the switch to each of the seven intermittent positions will activate the door ajar lamp and tone outputs for one second.
NOTE:
^ If Trouble Code 11 (No trouble codes are currently stored) is outputted and the condition still exists, there may be an open circuit. Refer to the wiring diagram for diagnosis of the open circuit.