B1306, B1307,B1308
Symptom: The soft top cannot be operated.
Potentiometer ( B1306 - Diode fault, B1307 - Feed overload, B1308 - Short circuit)
Fault symptoms
The soft top cannot be operated.
Conditions
B1306 Faulty diodes in the potentiometer, manufacturing fault.
B1307 Overload on pin 15 (K42) or 29 (K42).
B1308 Short to B+ or ground on pin 15 (K42) or 29 (K42)
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Note
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A diode fault between pins 1 and 3 on one of the potentiometers caused DTC B1308.
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Diagnostic help
The potentiometer values can be read on the diagnostic tool.
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Connect the diagnostic tool.
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Turn the ignition to position ON.
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Read the value for the relevant potentiometer
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If everything is functioning correctly, the diagnostic tool should display the current potentiometer values, which should lie between 15 and 240.
If all the potentiometer values are 0, the faulty potentiometer can be traced by disconnecting one potentiometer at a time until the values return to normal.
Check the wiring harness if diagnostic trouble codes are generated even though all the potentiometers have been disconnected.
The voltage on the control module potentiometer feed measured against ground should be:
pin 15 (K42)...........5.0 V
pin 29 K42).............< 0.1 V
Diagnostic procedure
1 Check the power supply to the potentiometers
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Unplug all the potentiometers.
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Turn the ignition to position ON.
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Measure the voltage with a multimeter on all the potentiometer connectors as follows:
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pin 1 - ground..................approx. 5V
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pin 3 and B+....................B+
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Are all the readings correct?
Continue with step 2.
Check and, if necessary, rectify the relevant lead. Continue with step 4.
2 Check the control module potentiometer inputs
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Connect the diagnostic tool.
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Turn the ignition to position ON.
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Connect a jumper lead in a connector as follows:
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between pins 2 and 1 the diagnostic tool should display.......approx. 250
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between pins 2 and 3 the diagnostic tool should display.......approx. 0
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Repeat the procedure with all three potentiometers.
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Are all the readings correct?
Continue with step 3.
Check and, if necessary, rectify the relevant lead. Continue with step 4.
3 Localize the faulty potentiometer
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Connect the diagnostic tool.
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Connect a potentiometer.
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Turn the ignition to position ON.
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Read the current potentiometer value.
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Is the reading plausible?
Repeat the procedure until all the potentiometers are connected. If the reading is plausible when all three potentiometers are connected, check and if necessary rectify the relevant lead. Continue with step 4.
Change the potentiometer. Continue with step 4.
4 Final check
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Clear the diagnostic trouble codes.
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Activate the soft top with the ROOF button and operate it for a few cycles
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Make sure the soft top is functioning correctly and that no diagnostic trouble codes are generated.
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Has the diagnostic trouble code recurred?
Change the control module as described in
The fault has been rectified.
