Each month in Diagnose This! we present a real-life service scenario with clues as to what the ultimate diagnosis was. If you think you know the answer, be the first to e-mail [email protected] with the correct response for free Truck Parts & Service merchandise. The answer will be revealed in a future issue of the magazine.
Vehicle: 2001 IH 4300
Key components: DT466 engine, Allison 2000 series transmission, air brakes
Scenario: This truck has an intermittent “check trans” light on, and shift scheduling changes when this occurs.
Clues:
- Scan data shows a U2105 “Can Buss Error” code.
- J1939 Datalink testing shows an intermittent varying resistance of 68-122 ohms with no pattern evident.
- The terminating resistors check out at 120 ohms each.
