Routing through rear bulkhead
Figure 24 - Front-to-Back Cable Routing in the EGS

2.12.

Continue routing and tie-wrapping the front-to-back cable through the rear bulkhead towards the next curbside
baselight (see Figure 25).

Routing through rear bulkhead
Figure 25 - Front-to-Back Cable Routing in the Rear Bulkhead Area
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Continue routing and tie wrapping the front to back cable through the rear bulkhead and through the curbside
baselights towards the rear of the bus (see Figure 26).

Routing through curbside baselights

Figure 26 - Front to Back Cable Routing in the Rear Curbside Baselights

2.14.

Continue routing and tie wrapping the front to back cable behind the Fire Suppression System (FSS). Insert
the APS cable segments with the cable glands separately into the two holes previously drilled in step 2.3.
Torque the cable glands to 3-4.5 N●m (see Figure 27).

APS 1 and APS 2 cable segments
from the front-to-back cable
Routing

Figure 27 - Front-to-Back Cable Routing in the +IB-X6499A Area (FSS Side)

2.15.

Rejoin the two APS cable segments within the convoluted tubing provided with the front to back cable wire kit.
Continue routing and tie-wrapping the front-to-back cable along harness 64 inside the engine compartment
(see Figure 28).

APS 1 & APS 2 segments from
the front-to-back cable

Figure 28 - Front-to-Back Cable Routing in the +IB-X6499A Area (Engine Compartment)
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2.16.

Raise the bus and continue routing and tie-wrapping the front to back cable over the same routing path
previously used for the bypass cable in level 1 (see Figure 29).

APS 1 and APS 2 segments
from the front-to-back cable

DEF reservoir

Figure 29 - Front-to-Back Cable Routing in the Hydraulic Oil Tank Area

2.17.

Continue routing and tie-wrapping the front to back cable down over the DEF reservoir towards the ECM
connector (see Figure 30).

ECM connector

APS 1 and APS 2 segments
from the front-to-back cable

DEF reservoir

Figure 30 - Front-to-Back Cable Routing to the ECM Connector

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Remove the two ECM connector strain relief screws, disconnect the ground splice connector and cut the 3
cable ties (see Figure 31).

Back shell
Cable
ties
ECM connector
screws
Figure 31 - Disassemble the ECM Connector

2.19.

Remove the ECM connector back shell and route the front-to-back cable towards the connector (see Figure 32).

ECM connector

Figure 32 - Front-to-Back Cable Routing to the ECM Connector

2.20.

Remove the electric cloth tape covering the wires entering the ECM connector. Disconnect wires at positions
9, 10, 33, 61 and 64 from the previously-installed bypass cable kit, then cut and tape back (see Figure 33).

Wires

Bypass cable

Figure 33 - Disconnect the Bypass Cable Terminals From the ECM Connector
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Slide in the two heat shrink tubing segments provided with the front to back cable wire kit over the end of
each APS cable segment. Use a heat gun to shrink the tubing at the extremity of each APS cable segment.
Insert the terminals from the front-to-back cable into the correct ECM connector positions. Use the wire color
and wire label as identification. For APS 1, use positions 9, 10 and 33. For APS 2, use positions 61 and 64
to install five of the six new wires of the front-to-back cable (see Figure 34).

Figure 34 - Positions to be Used for APS 1 and APS 2 Cable Segment Connections

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Locate the wire 95-238 (5V OEM sensor supply red wire) at position 8 of the ECM connector, measure 5
inches and cut the wire. Remove 1/2 inch of insulation at both ends of wire 95-238 and at the end of the
remaining red wire of the front-to-back cable and insulation on both the wire from postion 8 and the remaining
wire of the new wire kit. Install a solder sleeve (N93457-03) over the 3 wires and heat evenly until the solder
penetrates into the wires (see Figure 35).

Figure 35 - Install a Solder Sleeve for 5V OEM Sensor Supply Splicing

2.23.

Apply electric cloth tape over the front-to-back cable and the exposed wiring at the ECM connector. Install
the ECM connector back shell and the 3 cable ties. Connect the ECM connector to the ECM and install both
strain relief screws. Reconnect any splice connector disconnected earlier (see Figure 36).

ECM connector back shell

Apply electric cloth tape
Install screws

Cable ties
Figure 36 - Reassemble the ECM Connector

2.24.

Activate the vehicle's power supply.

2.25.

Close the battery compartment access door.

2.26.

Make sure that the engine starts properly.

2.27.

Make sure that the throttle pedal operates properly. .

2.28.

Make sure that no active fault codes are present.

2.29.

Stop the engine.

2.30.

Close all panels (rear panel, baselight panels, lateral console panel, front console panel, foot guard panel,
and driver partition panel) and ITS compartment.

2.31.

Return the bus to service. 
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APPENDIX 1 - GENERAL TROUBLESHOOTING PROCEDURE (ENGINE FAULT CODE 1242)
This troubleshooting procedure applies to Cummins Engine Fault Code 1242 (Accelerator Pedal or Lever
Position Sensor 1 - Data Erratic, Intermittent, or Incorrect).
There are several Fault Codes (FC) referring to Throttle Pedal Sensor issues. Whenever other TPS FCs are
logged along with 1242 FC, these other FCs should be troubleshot first. These other FCs correspond to TPS
wiring faults, such as open- and short-circuit, and are also likely to generate a 1242 FC. Detailed information
about these other TPS FCs can be found in the Cummins INSITE documentation.
Systematically proceed according to the following troubleshooting steps to identify what is causing the engine
1242 FC and to eventually eliminate this FC.

1. First connect to the Engine Control Module (ECM) with the Cummins INSITE diagnostic software tool to

check for the presence of FCs (verify if any 1242 fault code has been recorded in the ECM log). If one or
more 1242 FCs were logged, create a work order and save the ECM image.

2. Perform wiggle/pull tests on the TPS cables running in the bus cabin (check all interior locations) and in the
engine compartment to see if any FC occurs. Also carefully check every TPS cable connector along the
routing path (from throttle pedal to ECM) for any missing/damaged seal or terminal corrosion.

•
•

Remain logged onto Cummins INSITE and try to generate the 1242 FC or any other TPS FC.
Correct/repair if any wiring and/or terminal integrity issues are found. Then test drive the bus and
return it to service if the 1242 FC does not return.

3. Inspect to check if DCP-504300 was properly applied (see Appendix 2 for DCP-504300 instructions).
•
•

Production Change Order DCP-504300 was applicable to a large number of diesel buses built after the
BS3626E service document release (from lot L998 to lot LB32) but its application must be confirmed.
If DCP-504300 was not properly implemented, relocate the two TPS cable connectors further away
from the alternator by following the instructions provided.

4. Test the throttle pedal operation (see Appendix 3 for the throttle pedal testing procedure).
•
•

If the throttle pedal test fails with the 1242 FC, then replace the throttle pedal with a new or spare unit
(previously tested / known-good unit), test drive the bus and finally return it to service if the 1242 FC
does not return.
Otherwise, if all of the above troubleshooting steps have successfully passed and the 1242 FC still
returns, systematically proceed to check each of the following scenarios.

A. Check whether the original campaign BS3626E has been performed on the bus.








If YES, double-check that the BYPASS CABLE wire kit (Nova p/n N632000435) has been installed
according to BS3626E instructions and thoroughly inspect it for moisture intrusion (missing/leaking
connector seal or wire entry seal), connector damage or terminal corrosion.
If YES, the BYPASS CABLE wire kit has been on bus for a long period and 1242 FC still occurs, install a
new BYPASS CABLE wire kit and route it according to the LEVEL 1 INSTRUCTIONS specified in this
Information Letter.
If NO, install the BYPASS CABLE wire kit and route it according to the LEVEL 1 INSTRUCTIONS specified
in this Information Letter.
Test-drive the bus and return it to service if passing.
If the 1242 FC still returns in service, proceed to check scenario B.

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B. Check whether the BS3626E BYPASS CABLE wire kit has been installed AND routed according to the LEVEL 1
INSTRUCTIONS specified in this Information Letter.




If YES, double-check the BYPASS CABLE wire kit installation and thoroughly inspect it for moisture
intrusion (missing/leaking connector seal or wire entry seal), connector damage or terminal corrosion.
Test drive the bus and return it to service if passing.
If the 1242 FC still returns in service, proceed to check scenario C.

C. If, and only if, all of the above troubleshooting, testing (all tests pass and no 1242 FC can be generated) and
BYPASS CABLE wire kit LEVEL 1 installation work have been performed but 1242 FC still returns, proceed to
the following ultimate troubleshooting step and action.



Install a FRONT-TO-BACK CABLE wire kit (continuous TPS cable running from the throttle pedal to the
engine ECM) and route it according to the LEVEL 2 INSTRUCTIONS specified in this Information Letter.



Use the Nova Bus p/n N632000594 FRONT-TO-BACK CABLE wire kit for installation on a 40-ft bus.
Use the Nova Bus p/n N632000652 FRONT-TO-BACK CABLE wire kit for installation on a 60-ft bus.

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APPENDIX 2 - DCP-504300 PRODUCTION CHANGE ORDER

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APPENDIX 3 - THROTTLE PEDAL TESTING PROCEDURE (ENGINE FAULT CODE 1242)
This troubleshooting procedure applies to Cummins Engine Fault Code 1242 (Accelerator Pedal or Lever Position
Sensor 1 - Data Erratic, Intermittent, or Incorrect).
Perform the following throttle pedal tests with the bus ignition on, the engine stopped, and finally with the
engine running.
• Check several throttle pedal angular positions.
• Hold throttle pedal for 30 seconds.
• Try to replicate several scenarios that might occur in service.
When the engine is running, the throttle can be disabled by activating rear doors to engage throttle interlock.
This will prevent running the engine at full throttle in neutral for 30 seconds.

Conditions Required to Trigger the Cummins 1242 Fault Code
The Engine Control Module (ECM) detects that readings from Accelerator Position Sensor APS 1 and APS 2 differ
by more than 2%.
Note: Even though the APS 1 and APS 2 throttle pedal sensors are both powered by regulated 5 V voltage sources
supplied by the ECM, the APS 1 output signal range is twice that one of APS 2. This is why a full throttle condition
corresponds to an APS 1 reading of 4.25 V and to APS 2 reading of 2.13 V in the following figures.

Throttle Pedal Testing Procedure
After the following two preliminary steps, proceed with the test sequence presented on the next page while
applying the specified pass/fail criteria and referring to the key observations detailed.
• Log onto INSITE to test the throttle pedal.
• Pull up APS 1 & APS 2 data readings from the INSITE log.

Figure A3.1.

Log onto INSITE to Test the Throttle Pedal
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Throttle Pedal Test Pass/Fail Criteria
• APS 1 and APS 2 signal readings should vary smoothly according to the throttle pedal angular position.
• APS 1 and APS 2 signal readings should be stable when the throttle pedal position does not change.
• The APS 1 signal reading should always be twice as much as the APS 2 signal reading.

Throttle Pedal Test Sequence
1. Test the bus with engine OFF.
• Exercise the throttle pedal.
o Observe the INSITE throttle pedal readings, especially the APS 1 and APS 2 voltage readings.
o Depress the throttle pedal and hold for 30 seconds.
 APS 1 and APS 2 voltage readings should remain stable.
2. Test the bus with engine ON.
• Open back door to enable the throttle interlock in order to disable the engine throttle.
• Exercise the throttle pedal.
o Observe the INSITE throttle pedal readings, especially the APS 1 and APS 2 voltage readings.
o Depress the throttle pedal and hold for 30 seconds.
 APS 1 and APS 2 voltage readings should remain stable.

Key Observations at Full Throttle Position
• Good APS 1 (PASS condition):
 Reading is 4.25 V and steady when throttle pedal fully depressed.
• Bad APS 1 (FAIL condition):
 Reading is unstable with throttle pedal being held steady.
• Bad APS 1 (FAIL condition):
 Reading is around 4.19 V (low).
• Good APS 2 (PASS condition):
 Reading is 2.13 V and steady when throttle pedal fully depressed.
• Bad APS 2 (FAIL condition):
 Reading is unstable with throttle pedal being held steady.
• Bad APS 2 (FAIL condition):
 Signal 2 is about 2.03 V (low).
Note: Any of the abovementioned bad APS readings (FAIL condition) should normally lead to 1242 FC activation.

Throttle Pedal Testing Procedure Background
• The TPS readings specified above have been collected through several throttle pedal sensor 1242 FC
investigations.
• This testing procedure might not be 100% accurate but many field tests have shown it to be dependable.
• This testing procedure is an efficient first step towards permanently resolving 1242 FC issues.

Throttle Pedal Test Records
• Capture and save screenshots of any failing APS readings.
• Examples of typical APS 1 and APS 2 good and bad reading values are presented in the following figures.

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Example of INSITE Normal (PASS) Readings at Idle and Full Throttle Positions

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Figure A3.3.

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Example of INSITE Abnormal (FAIL) Readings at Full Throttle Pedal Position
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