On my 95 4X4 EB, the 4WD on the fly seems to work O.K., however, after the
4WD light comes on briefly, it goes out - then the 4WD and 4WD LOW lights flash six times, the lights go out for a while and the six flashes repeat. (The 4WD LOW also seems to be working OK, but the 4WD and 4WD LOW flash in the same way, when in 4WD LOW).Any thoughts on the possible problem would be appreciated.
TIA
--Frank
In the '95 models of Control Trac the 4WD system had a 2WD mode and a
4WD-Auto and 4WD-Lo mode. The transfer case clutch pack was pulsed by the GEM system in response to differential speeds of the front and rear driveshafts in the Auto mode. The system starts at around 10% engaged and increases the engagement period in roughly 10% increments until rear wheel slippage is stopped. If the system detected something odd, like the back going faster than the front even after reaching 100% engaged then the system flashes the 4WD and 4WD-Lo lights to alert the driver of a problem. In the '95-'96 models I believe the failure mode is 100% engaged in the 4WD positions, so you will still have 4WD, but only for use off pavement. Usually the problem is with one of the speed sensors, but dirty contacts could also cause this. God Luck!=Vic= Bear Gap, PA
FS wrote:
FWIW, I experienced the exact same thing. What Vic describes is I what I've heard as the problem as well. I checked my sensor contacts, and they were fine. Next step is to remove the sensor assembly for the front driveshaft (from the transfer case) and see if it's gummed up or dirty. If cleaning the sensor doesn't fix it, then I may have to replace the front driveshaft speed sensor. I think what's happening is that we're gettting a sporadic signal (or no signal at all) from the speed sensor on the front driveshaft rotation speed. Therefore, the system, as Vic describes, locks up full 100% because it thinks the rear driveshaft it spinning still, and thus we also get the flashing dashboard lights as you describe. We have experienced this lockup as well. If you drive on dry pavement under these conditions you can hear the clutch packs groaning/slipping as you turn (probably designed as relief so you don't snap an axle shaft). Still, not a particularly healthy thing for the 4wd system so we leave it in 2wd for now, until I fix it. I priced out a new sensor at AutoZone (or was it the Ford dealer?) and it was about $65. Seems easy to replace, but I'd check the contacts first and then pull the sensor itself to see if it's dirty. Per the shop manuals, the sensor actually reads off a notched gear-like ring attached to the front driveshaft just inside the transfer case housing. It's supposed to pick up "pulses" a lot like how an ABS system picks up pulses to determine if all 4 wheels are turning at the same rate.
Mike
"Vic Klein" wrote in message news: snipped-for-privacy@ptd.net...
I have cleaned the sensors and they "look" OK. I did have the front right sensor replaced at the dealer about 4 months back. Seemed OK after that, but I have not used the 4X4 mode much since then. Thanks for the information.... and I do have the same symptom, sure feels like I am at 100% power to the front wheels.
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