This ACM2.1 Post Run Lamp sheet covers Detroit SPN 3490 FMI 3, set by an open circuit on pin 14 of the Aftertreatment Control Module 120-pin connector. It states the repair and the condition under which the circuit exists. It is a short wiring reference.
Official document details
| Brand | Detroit |
|---|---|
| Model coverage | DD Series (EPA 2007-Current); also filed under Series 60 (DDEC VI – EPA 2007) |
| System / Group | DTCs — Post Run Indicator Lamp |
| Fault code | SPN 3490 / FMI 3 |
| Source | www.TruckFaultCodes.com (© 2017) |
| Pages | 1 |
| File size | 0.1 MB |
| Format | |
| Language | English |
ACM2.1 Post Run Lamp diagnostic guide
The document indicates an open circuit on the pin 14 circuit of the ACM2.1 120-pin connector and directs the technician to repair that open, referring to Original Equipment Manufacturer (OEM) literature for the wiring schematic. A note limits the process lamp to trucks fitted with a negative battery disconnect system. There are no numbered steps; the value is in identifying the exact circuit so the open is repaired at the right pin rather than guessed at.
Document table of contents
- Fault code identification: SPN 3490, FMI 3
- Description of the process lamp circuit
- ACM2.1 pin 14 open-circuit repair
- Negative battery disconnect system note
Applicable truck models
This procedure applies to Detroit DD Series engines built for EPA 2007 and later, covering GHG14 calibrations as printed on the document cover, and the identical SPN/FMI sheet is also filed under Detroit Series 60 (DDEC VI, EPA 2007). Confirm the emissions platform on your truck and cross-check the connector and pin numbers against the official Detroit engine support site before making any repair.
Who needs this ACM2.1 Post Run Lamp manual
An electrical technician on a GHG14 Detroit truck with negative battery disconnect uses this sheet to locate and repair the open on the correct aftertreatment module pin instead of the lamp itself.
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