Engine Control Module (ECM) Malfunctions Due to Incorrect Switch Input Wiring

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Technical Service Bulletin Number
TSB120060

Technical Service Bulletin

Subject
Engine Control Module (ECM) Malfunctions Due to Incorrect Switch Input Wiring

Issue
Symptom




Engine control module (ECM) switch inputs, such as the power take-off
(PTO)/Accelerator Interlock/Oil Pressure switch, are inoperable.
Fault Codes 175, 176, and 415 (ISB Only) are common on CM2350s with incorrect
switch wiring.

Root Cause


The ECM switch inputs are wired incorrectly.

This document directs the field to inspect the ECM switch to ground input wiring to make sure
the inputs are connected to ground and to prevent ECM malfunctions due to this issue.

Verification
For CM2250 Modules:
Perform the following steps to check and verify that the ECM switch inputs are wired correctly.



Remove the original equipment manufacturer (OEM) connector from the ECM.
Use a multimeter to measure for voltage between pins 24 through 30, 36 through 40, 49,
50, 59, 60, and ECM switch RETURN pin 19 at the OEM harness connector.

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Engine Control Module (ECM) Malfunctions Due to Incorrect Switch Input Wiring

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NOTE: The specific pins used in the connector depend on what switches were installed
by the OEM.


Toggle the switch to ground inputs and check for battery voltage with the keyswitch in
both the ON and OFF positions.

The multimeter must show no voltage. If any voltage is observed, the switch must be wired
correctly before the ECM is installed.
Reference the circuit diagram or wiring diagram for connector pin identification.
Use the following procedure for general multimeter usage techniques. Refer to Procedure 019359 in Section 19 of the appropriate service manual
For CM2350 Modules:
Perform the following steps to check and verify that the ECM switch inputs are wired correctly.



Remove the OEM connector from the ECM.
Use a multimeter to measure for voltage between pins 11, 12, 19, 20, 43, 44, 47, 66
through 70, 86 through 94, and ECM switch RETURN pin 62 at the OEM harness
connector.
NOTE: The specific pins used in the connector depend on what switches were
installed by the OEM.



Toggle the switch to ground inputs and check for battery voltage with the keyswitch in
both the ON and OFF positions.

The multimeter must show no voltage. If any voltage is observed, the switch must be wired
correctly before the ECM is installed.
Reference the circuit diagram or wiring diagram for connector pin identification.
Use the following procedure for general multimeter usage techniques. Refer to Procedure 019359 in Section 19 of the appropriate service manual.
For CM2250 and CM2350 Modules:
NOTE: The resistance measurement given in this document of 0.020 Ohms is different
than the Service Manual specification.
Perform the following steps to check and verify that the ECM power return (ground) wires are
grounded correctly.





Disconnect the batteries. See equipment manufacturer service information.
Use a multimeter to measure the resistance between the OEM connector ECM ground
return pins and Battery (-) cable connection.
The multimeter ohm reading must be less than 0.020 Ohms. If reading is not less than

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Engine Control Module (ECM) Malfunctions Due to Incorrect Switch Input Wiring






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0.020 Ohms, the high resistance ground connection must be corrected.
Reconnect batteries. See equipment manufacturer service information.
With all components connected, use a multimeter to measure the voltage between the
engine ECM block ground stud and battery negative connection with the following
conditions met in order:
 Key off
 Key on; engine not running
 Key on; engine running and electrical accessories on
The multimeter must show less than 0.5VDC. If voltage is not less than 0.5VDC, the
high resistance ground connection must be corrected.

Reference the circuit diagram or wiring diagram for connector pin identification.
Use the following procedure for general multimeter usage techniques. See the corresponding
Service Manual. Reference Procedure 019-359 in Section 19.

Resolution
If any of the pins show a voltage with the multimeter when the switches are toggled, the switch
must be wired correctly, so an open or ground is observed. If the ECM is installed before the
switch is wired correctly, the ECM will be susceptible to repeat malfunctions.
NOTE: Subsequent damage to the ECM, caused by failure to rewire the incorrectly wired
switches prior to ECM installation, will not be warrantable.
ECM power return (ground) wiring must be connected to the engine block ground stud and
then return from the engine block to the battery by a low resistance circuit of 0.020 Ohms or
less between the ECM and battery.
Sustained voltage differential or peak-peak voltage differential levels between the engine ECM
block ground stud and battery negative not to exceed 0.5VDC.

Warranty Statement
The information in this document has no effect on present warranty coverage or repair
practices, nor does it authorize TRP or Campaign actions.

Document History
Date
2012-2-29
2012-3-27
2012-10-5
2013-12-5
2014-6-10

Details
Module Created
QSOL Quick Fix|Reason: Spelling Error|Notes: none
QSOL Quick Fix|Reason: Incorrect Part Number|Notes: none
Add CM2350 Pins
none

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4/5/2016

Engine Control Module (ECM) Malfunctions Due to Incorrect Switch Input Wiring

2016-3-17

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Added ground wiring verification for CM2250 and CM2350 Modules.

Last Modified: 28-Mar-2016
Copyright © 2000-2010 Cummins Inc. All rights reserved.

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4/5/2016