I have a 2001 Safari Cheetah on the Magnum Velvet Ride chassis, Cat 3126, Allison MH3000 transmission, hydraulic brakes and Pacbrake.
When the engine is started, the red ABS light may be on or off. However, when the transmission is put in gear and the motor home begins moving, the red ABS light will be off. It will stay off for an indefinite time (5 minutes to ??). While the red ABS light is off, the engine retarder (exhaust brake/Pacbrake) is inoperative. When the red ABS light comes back on, the exhaust brake functions normally (exhaust brake switch on and accelerator off above 15 mph, exhaust braking is activated and transmission commanded to 2nd gear and steps down as slowing permits).
Also, when the ABS light is out and the exhaust brake is inoperative, the transmission runs hot (about 200 degrees). It appears that when the ABS light is out, the transmission stays in 5th gear, thus the higher temperature (engine RPM is 200-300 higher than normal at highway speeds). When the ABS light is on and the exhaust brake functions normally, the transmission temperature runs normally (about 140 degrees).
Local shops are unable to find the problem. There are no codes on transmission or engine ECUs. Any ideas?
