I have an 06, 4.6L less than 18,000 miles on it. Was stored in a garage. Bought it used with a known problem with the ABS/traction control.
The ABS, traction control and power train lamps all come on once the car get above 30 or so MPH. They may go back off and come back on at random. If the car is started, running, in park, I can activate/deactivate the traction control fine.
Hooked up the scan tool and it was reporting the left rear wheel sensors was not reading correct. Driving around I can see the speed on this one input glitch every so often. Appears random and not tied to road conditions. At higher speeds problem is worse. At for example, 45 MPH I may see dips of 5-6 MPH on this input. It never reads higher, always lower.
I pulled the two rear sensors and using a 1K ohm resistor and a power supply looked across the sensors with a scope. Both seem to switch between half the supply and the supply voltage. Removing the sensors will cause a different error so it must detect shorts, opens and in-range.
The toothed ring appears fine. Put car on lift and rotated wheel, no warps or chips. No build up on the sensors. Gaps are about the same, but when I tested the two sensors on the bench, they appear very robust as far as the range of gap they will work at. Sensors are made by Bosch.
Inspected harness from the sensor for about 6' and it all appears good. No signs of anything rubbing on it anywhere. Looked at the harness under hood area, all appears fine.
Replacing the sensor with a new one had no effect other than make my wallet thinner.
The speedometer and cruse control work fine. No other problems I see with it.
It would seem like a break in the harness but all the connectors look great and harness itself seems fine. Looking in a Chilton's manual, there is no information on the ABS including the wiring for it.
PO said that it started doing this at random just before they put it into storage last year. They took it to the dealer for the last oil change and asked about the problem. Dealer stated they could not find a problem and to just see if it clears up. Not sure what that means but getting it second hand.
Any ideas on what could be the cause would be great. I am to the point I think I will have to take it in to a Ford dealer.
The ABS, traction control and power train lamps all come on once the car get above 30 or so MPH. They may go back off and come back on at random. If the car is started, running, in park, I can activate/deactivate the traction control fine.
Hooked up the scan tool and it was reporting the left rear wheel sensors was not reading correct. Driving around I can see the speed on this one input glitch every so often. Appears random and not tied to road conditions. At higher speeds problem is worse. At for example, 45 MPH I may see dips of 5-6 MPH on this input. It never reads higher, always lower.
I pulled the two rear sensors and using a 1K ohm resistor and a power supply looked across the sensors with a scope. Both seem to switch between half the supply and the supply voltage. Removing the sensors will cause a different error so it must detect shorts, opens and in-range.
The toothed ring appears fine. Put car on lift and rotated wheel, no warps or chips. No build up on the sensors. Gaps are about the same, but when I tested the two sensors on the bench, they appear very robust as far as the range of gap they will work at. Sensors are made by Bosch.
Inspected harness from the sensor for about 6' and it all appears good. No signs of anything rubbing on it anywhere. Looked at the harness under hood area, all appears fine.
Replacing the sensor with a new one had no effect other than make my wallet thinner.
The speedometer and cruse control work fine. No other problems I see with it.
It would seem like a break in the harness but all the connectors look great and harness itself seems fine. Looking in a Chilton's manual, there is no information on the ABS including the wiring for it.
PO said that it started doing this at random just before they put it into storage last year. They took it to the dealer for the last oil change and asked about the problem. Dealer stated they could not find a problem and to just see if it clears up. Not sure what that means but getting it second hand.
Any ideas on what could be the cause would be great. I am to the point I think I will have to take it in to a Ford dealer.