26-001 DDC DT12 Range Detent Diagnostic
Models:
General Information
Some DT12 shifting complaints may be corrected by installing the updated Range Detents.
Complaint may be described as:
•

The transmission shifts into neutral when attempting a range up or down shift (complaint may be a 5 to 7 shift, 6
to 8 shift or any other shift combination where a low-to-high range is required).

•

A grinding noise.

Parts Table

Part Number

Part Description

Quantity

A9602670874

Split Detent

2

Table 1, Parts Table

Repair Procedure
1. Obtain a driving log file of the vehicle going through all the gears.
NOTE: The CPC5 SPN 521063/14 fault code (active or inactive) may also be present in the log.
2. Navigate to the ‘Identification’ screen, under 'Stored Data'. Look in ‘TCM 22-22-21’ for reversing events
(events counter is usually greater than 30 and as high as 700). See 1,Range Reversing Events, and chart the
log file to identify range 'hang-up/intermediate' position. See 2,Monitored Instruments. Does the events counter read 0 or does the chart show the range in an intermediate position?

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Published by
Detroit Diesel Corporation
13400 Outer Drive, West
Detroit, Michigan 48239-4001
Printed in U.S.A.

Fig 1, Range Reversing Events

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Published by
Detroit Diesel Corporation
13400 Outer Drive, West
Detroit, Michigan 48239-4001
Printed in U.S.A.

A. TCM5 2313 Desired Gear from CAN
B. TCM5 1F1B Gear Information Actual Gear
C. CPC5 AS: Actual Engine Speed
D. TCM5 2306 Split Actuator Actual Position
E. TCM5 2309 Range Actuator Actual Position
Fig 2, Monitored Instruments

2.a

Yes; see Range Up or Down Shift Issue and continue trouble shooting.

2.b

No; go to step 3..

3. Remove and inspect the detents. See Removal of the Range Detent. Is the detent type with the red X installed
(see below image)?

, ()

Published by
Detroit Diesel Corporation
13400 Outer Drive, West
Detroit, Michigan 48239-4001
Printed in U.S.A.

Fig 3, Detent Types

3.a

Yes; replace both detents and go to step 4..

3.b

No; reinstall the equipped detents and go to step 4.. See Installation of the Range Detent.

4. Remove the range piston cylinder. see Removal of the Range Cylinder.
5. After removing the range piston cylinder, actuate the range piston by repeatedly pulling and pushing on the
piston (by hand) to confirm that the detents are seated on the rod. The rod should not move freely or easily
when pulling and pushing the range piston by hand. Does the range piston rod move freely?
5.a

Yes; replace the transmission. See Removal of the Transmission.

5.b

No; see Range Up or Down Shift Issue to continue trouble shooting.

Warranty
Normal in-warranty procedures apply.

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Published by
Detroit Diesel Corporation
13400 Outer Drive, West
Detroit, Michigan 48239-4001
Printed in U.S.A.

Note :
Component Code / VMRS = 026-010-093 - CATCH BOLT - DETENT, SHIFT
Component Code / VMRS = 026-015-002 - ASSEMBLY - COMPLETE, AUTOMATED TRANSMISSION

CONTACT INFORMATION
For questions, please create a Service Technical Request using the DTTS Application on the DTNA Portal.

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Published by
Detroit Diesel Corporation
13400 Outer Drive, West
Detroit, Michigan 48239-4001
Printed in U.S.A.