SPN 558 FMI 6 is a Detroit fault code reference sheet that documents the idle validation switch 2 circuit failed high (an open circuit) 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 Idle Validation Switch (IVS) 2 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 | 558 |
| Failure Mode Identifier | 6 |
| Emissions revision | GHG14 |
| Source | Detroit fault code sheet (© 2017, www.TruckFaultCodes.com) |
| Pages | 2 |
| File size | 0.28 MB |
| Format | |
| Language | English |
SPN 558 FMI 6 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:
- Disconnect the Idle Validation Switch (IVS), turn the ignition ON, and measure the voltage between IVS pins 4 and 6.
- Use the voltage readings at IVS pin 4 and pin 5 to ground to locate an open wire between the Common Powertrain Controller (CPC4) #1 connector and the IVS.
- Measure the resistance between CPC4 #2 pin 2 and IVS pin 6 to confirm the open in that leg.
- If the wiring checks good, replace the IVS following the Original Equipment Manufacturer (OEM) procedures.
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 558 FMI 6 manual
This SPN 558 FMI 6 manual is written for diesel technicians and DD Series fleet owners who are isolating an open circuit on the idle validation switch 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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