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Automotive HD/Fleet Forum

Professional automotive forum for discussion of heavy-duty trucks, buses and other on- and off-road equipment, and maintenance of automotive fleet vehicles. Discussion topics include fuels and lubricants, hydraulics, performance, on-board diagnostics, powertrain, power distribution, anti-lock braking and stability control systems, and best practices as they relate to heavy duty and fleet maintenance. This forum is for experienced automotive repair professionals only, membership required.

Continue to the description of our next automotive discussion forum, the HVAC Forum.

Recent Automotive Discussions in the Automotive HD/Fleet Forum

lost memory
03/26/2024 in the HD/Fleet Forum
This is interesting. We have an IC Coach CE 300 (Navistar) that lost the speedo. OK, checked a few things, no speed signal which turned into to no hi or lo CAN communications with the ECM. Still working on that, but what is interesting is the apparent com...
6.7 isb exhaust brake cm 2350
03/25/2024 in the HD/Fleet Forum
[Driveability: 21 IC Corporation CE School Bus 5.9L] Exhaust brake does not work. Insite is not showing any response from switch.cummins wiring diagram seems to show a 12 volt signal at ecm from the switch. The oem switchpack appears to send the signal v...
2001 Western Star 4900 Cat 3406E No Odometer
03/20/2024 in the HD/Fleet Forum
Hello and thanks for taking the time to read this. I'm posting for another shop and the problem is the digital odometer is blank yet the speedometer works properly. The speedometer has been replaced with a new assembly and another used assembly from anoth...
Speedometer and Tach
03/20/2024 in the HD/Fleet Forum
[Electrical: 07 GMC C5500 Topkick C5C042 6.6L] Group, Looking for some help with this truck. while driving, the speedo and tach will intermittently bounce around. We have had the dash cluster out for repair, then back for a re check with no problem found...
Trivia Only: What is Alvin Crow singing here?
03/17/2024 in the HD/Fleet Forum
I'm hoping somebody might recognize this. I linked a couple seconds early, it comes at 58 seconds. "He's double clutching that old "(what?) through fifteen gears into high.".

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