Hello Fellow Foretravelers. My 1989 U300 with a 6V92 is kicking my ass. The engine starts but seems to be in limp mode. Idles a little rough and revs sluggishly. I check for low coolant checked the fuel water separator for water (wasn't any) changed the secondary filter with no success.
I did some welding on the coach as I have done before. I disconnected the alternator, chassis batteries, and house batteries before welding. This has never been a problem in the past.
Any thoughts?
Thanks Andy
Limp mode is usually because of a sensor returning low coolant, low voltage, or other fault codes to the ECU. Flip the engine code switch under the dash and count the light bulb flashes. Compare that to the DDEC II fault codes on the attached PDF.
DETROIT DIESEL Electronic Controls DDEC-II Diagnostic Codes - Wanderlodge... (http://www.wanderlodgeownersgroup.com/forums/showthread.php?t=6879)
Pierce
An air leak in the diesel supply hose from the tank can also duplicate your symptoms. Does it idle at 600 rpm smoothly?
P
Check ECM fuses if you blew one of the fuses it will only run on 3 cylinders
Andy,
Any smoke or stalling after start-up? Like Pierce says absent a fuel or air restriction the codes will point us in the right direction.
Jerry
Interesting, I didn't know that.
I believe the fuses are located on the 12 volt panel in the bays (mine is in the utility bay, drivers side, forward wall).
According to the schematic there are 3 fuses (5 amp and two 20 amps). Pic has a rectangle drawn around them.
I love all you folks! I'll dig in again with this new wisdom and let ya know.
As always thank you for taking the time to help out!
Im going to name my next dog John Fitz! When I took the battery box cover off I must have hit one of the fuse holders and knocked the fuse out. It would have taken me a week to figure that out!!
I'm giddy!
Thank you all again!
Glad to hear that.
Stump is your hero. I would have never figured the ECM was split like that. Now I'm wondering what that 3rd fuse does.
The 5 amp fuse powers off the ign key,it powers the circuit for cruise etc. The 2 20amp Fuses are the main ECM power supply fuses. each fuse powers each bank independently.
Right! A hearty thank you Stump!
Here is a DDEC II wireing diagram.You can see snd follow the 5 amp fuse circuit.