Part 1
Checking disconnected stop (brake) light circuit
Checking the stop (brake) light switch
Connection
Connection of Volvo Scan Tool (ST)
Volvo ST must be connected to both VIDA PC and vehicle to DLC in passenger compartment (models 1996-) or DLC B (models -1995).
Is Volvo ST connected and switched ON?
Yes - FAULT FOUND
No - No Fault Found
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FAULT FOUND - Checking response code
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Checking response code
- Ignition on.
- Activate Diagnostic Test Mode (DTM) 2.
- ON/OFF switch to the OFF position
- Depress brake pedal.
- Check that the stop (brake) light switch is OK by checking that response code 1-3-2 is returned.
Response code 1-3-2 returned?
- 1. Yes, response code 1-3-2 is returned.
- 2. No, response code 1-3-2 is not returned.
- 3. No, response code 3-1-1 is returned instead.
Select one of the alternatives above.
1 - No Fault Found
2 - Checking the stop (brake) light
3 - Checking response code 3-1-1
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Checking response code 3-1-1
A response code is returned when the control module receives several input signals from the same component or circuit within 8 ms. The cause of the fault can be loose connections or a defective system component.
Continue - Checking the stop (brake) light
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Checking the stop (brake) light
- Ignition on.
- Depress brake pedal.
Does the stop (brake) light light?
Yes - Checking power supply to control module
No - Checking fuse
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Checking fuse
- Check that fuse 11/12 is intact.
Is the fuse intact?
Yes - Checking 30-supply to fuse
No - Checking for a short-circuit
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Checking for a short-circuit
- Ignition off.
Check cable between:
- fuse 11/12 and stop (brake) light switch connector terminal 1
- stop (brake) light switch connector terminal 2 and stop (brake) lights
- stop (brake) light switch connector terminal 2 and control module connector terminal 6S for a short-circuit to ground according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.
Continue - Verification
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Checking 30-supply to fuse
- Ignition on.
Connect a voltmeter between the rear socket of the fuse holder for fuse 11/12 and ground.
The voltmeter should read battery voltage.
OK - Checking power supply to stop (brake) light switch
Not OK - Checking for an open-circuit
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Checking for an open-circuit
- Ignition off.
- Check the cable between battery positive terminal and fuse 11/12 for an open-circuit according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.
Continue - Verification
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Checking power supply to stop (brake) light switch
- Ignition off.
- Disconnect stop (brake) light switch.
- Ignition on.
Connect a voltmeter between stop (brake) light switch connector terminal 1 and ground.
The voltmeter should read battery voltage.
OK - Checking the stop (brake) light switch
Not OK - Checking for an open-circuit
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Checking for an open-circuit
- Ignition off.
- Check cable between fuse 11/12 and stop (brake) light switch connector terminal 1 for an open-circuit according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.
Continue - Verification
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Checking the stop (brake) light switch
- Ignition off.
- Connect stop (brake) light switch.
- Ignition on.
Connect a voltmeter between stop (brake) light switch connector terminal 2 and ground.
Voltmeter should read battery voltage when the brake pedal is depressed more than 5-10 mm.
OK - Checking the stop (brake) light bulbs
Not OK - Adjusting the stop (brake) light switch
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Replacing component
- Ignition off.
- Try a new control module according to Replacing control module Service and Repair.
Continue - Verification
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Checking the stop (brake) light bulbs
- Ignition off.
- Check that stop (brake) light bulbs are intact. Replace if necessary.
- Disconnect stop (brake) light switch.
Connect an ohmmeter between stop (brake) light switch connector terminal 2 and ground.
The ohmmeter should read approx. 0 ohms.
OK - Checking response code
Not OK - Checking for an open-circuit
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Checking for an open-circuit
- Ignition off.
- Check cable between stop (brake) light switch connector terminal 2 and stop (brake) light bulbs for an open-circuit according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault. If no fault is found replace the bulb failure warning sensor.
Continue - Verification
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Checking response code
- Ignition off.
- Connect stop (brake) light switch.
- Ignition on.
- Activate Diagnostic Test Mode (DTM) 2.
- ON/OFF switch to the OFF position
- Depress brake pedal.
- Check whether response code 1-3-2 is returned.
Response code 1-3-2 returned?
Yes - FAULT FOUND
No - Replacing component
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