Kalmar - MSARB Tonal Alarm Diagnostic

Modified on Fri, 13 Feb at 2:53 PM

1. Fault Overview

A yellow and black circle with black text

AI-generated content may be incorrect. When the LCD screen ‘Fault Detected’ menu option displays a Tonal Alarm Fault, and the MSB Fault Light remains constantly illuminated when the ignition is turned to ON (right),

Access MSB and Screen Faults sub-menu by pressing and holding red fault symbol on screen or via holding the menu button for 3 seconds.

Horn over current

Horn open circuit

The fault conditions will be one of below:

Conditions for setting fault

Disconnected/faulty tonal alarm
Open/short circuit in wiring harness
Internal MSB ECU fault.

After completing diagnosis and rectifying any faults, a full system test must then be performed and documented on the Systems Confirmation Test – MAX-SAFE Anti-Rollaway Brake System test sheet prior to returning the vehicle to service.

2. Diagnostic Procedure

Leave park brake applied while carrying out the following tests.

STEP 1: Clear the fault by isolating the vehicle power supply at the batteries for at least 1 second. Reactivate the power supply to the vehicle.

Fault re-occurs on reactivating power supply: Continue to STEP 2 (Testing for an open circuit).

Fault does not occur upon reactivating power supply: Continue to STEP 5 (Testing for a short circuit).

STEP 2: Disconnect the tonal alarm. Bridge the 2 tonal alarm wires together. Isolate the vehicle’s power supply for a minimum of 1 second, and then re-connect the power supply.

Fault re-occurs on reactivating power supply: Continue to STEP 3.

Fault does not occur upon reactivating power supply: Replace tonal alarm.

Verify repair with Full System Test.

STEP 3: Locate MSB ECU. Disconnect the 12-pin Deutsch Connector (black). Using a multi-meter, measure resistance between Pin 12 (orange/white) and Pin 1 (orange/white) of tonal alarm connector (H-Horn).

Verify GND circuit on pin 2 of tonal alarm connector.

Within specifications: Continue to STEP 4.

Not within specifications: Repair wiring harness/connections as required.

Verify repair with Full System Test.

STEP 4: Replace tonal alarm. Perform a Full System Test.

If the fault still appears: The ECU has failed. This scenario is unlikely: repeat all testing again to ensure that it is the ECU that has failed. If all testing has been repeated and testing still indicates that the ECU has failed, replace the ECU.

Verify repair with Full System Test.

STEP 5: (Testing for a short circuit)

With the tonal alarm reconnected, isolate and reactive the vehicle power supply; identify that the LCD screen is not displaying a fault. Operate the system and activate the Tonal Alarm circuit by remaining ON the seat, UNBUCKLING seatbelt, and DISENGAGING the vehicle's park brake. Ensure that the alarm sounds whilst the seatbelt is UNBUCKLED and the park brake is OFF. Perform this cycle test until the system faults or until the 10 cycles have been completed.

Fault does not occur upon reactivating power supply: Perform a Full System Test.

Fault re-occurs when Alarm circuit activated: Continue to STEP 6.

STEP 6: Locate MSB ECU. Disconnect the 12-way Deutsch Connector (black). Using a multi-meter, measure resistance between Pin 12 (orange/white) and Pin 1 (orange/white) of tonal alarm connector.

Verify GND circuit on pin 2 of tonal alarm connector (H-Horn).

Checking for shorted wiring to ground.

Within specifications: Continue to STEP 7.

Not within specifications: Repair wiring harness/connections as required.

Verify repair with Full System Test.

STEP 7: Replace tonal alarm. Perform a Full System Test.

Verify repair with Full System Test.

4. Full System Test

Undertake a full system test of the MAX-SAFE Brake System and document the results on the test sheet found within the document Systems Confirmation Test – MAX-SAFE Anti-Rollaway Brake System prior to returning the vehicle to service.

Should the testing outlined within the Systems Confirmation Test fail for any reason, the system must be thoroughly inspected, diagnosed and repaired, as per the relevant Diagnostic Process document, prior to the vehicle being returned to service.