SPN 571 FMI 4 is a Detroit fault code reference sheet that documents the engine brake disable push-button shorted to ground or pressed too long diagnostic for DD Series engines built to EPA 2007 and later emissions standards. This single-topic page reproduces the factory-style test order Detroit dealers and independent shops follow for the engine brake disable push-button circuit, from confirming related codes through to the final repair decision.
Official document details
| Brand | Detroit |
| Model coverage | DD Series (EPA 2007-Current) |
| System / group | Diagnostic Trouble Codes (DTCs) |
| Suspect Parameter Number | 571 |
| Failure Mode Identifier | 4 |
| Emissions revision | GHG14 |
| Source | Detroit fault code sheet (© 2017, www.TruckFaultCodes.com) |
| Pages | 2 |
| File size | 0.22 MB |
| Format | |
| Language | English |
SPN 571 FMI 4 troubleshooting steps
The sheet lists the ordered checks Detroit publishes for this code, so a technician can rule out network and power-supply faults before condemning a switch, sensor or module. The main steps are:
- Check for Common Powertrain Controller (CPC4) codes SPN 168 / FMI 0, 14 or 18 (battery voltage), and for Motor Control Module (MCM2.1) SPN 625 / FMI 9 on the Controller Area Network (CAN).
- Confirm whether the CPC4 has been recently reprogrammed; if not, clear the fault and retest.
- With the ignition ON, check whether the active fault returns; if it does, disconnect CPC4 connector #4.
- Measure the resistance between CPC4 connector #4 pin 18 and ground: below 1k ohm, repair the wire to the push-button; otherwise replace the engine brake disable push-button switch.
Applicable truck models
This code applies to Detroit DD Series diesel engines (EPA 2007 to current) and, for the shared driveline codes, to Series 60 (DDEC VI) installations that use the same Common Powertrain Controller and Motor Control Module architecture. Coverage is defined by the engine and control-module configuration rather than the truck badge, so confirm the exact build against the current model line on the Detroit Diesel official website.
Who needs this SPN 571 FMI 4 manual
This SPN 571 FMI 4 manual is written for diesel technicians and DD Series fleet owners who are isolating a shorted or stuck engine brake disable push-button and want the exact Detroit test order before ordering parts. Following the documented sequence keeps unnecessary sensor and module replacements to a minimum.
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