Mobile Home Warning Light

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The OBD2 port is on the right side of the steering column, usually up out of site behind the dash since the coach manufacturers seldom relocate it as Ford directs them to. Look carefully, it has a rectangular black cap on it. Here's a photo of the location with the dash removed for clarity.
 

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OK, here is what I got.
One code came up: P0720  Output Speed Sensor Circuit
What do you guys think?
 
As Gary RV_Wizard mentioned, the next start up the light should go out.
I just checked by turning the ignition on. The light is still on. I should disconnect the battery?
Would hitting the disconnect breaker shut it off?
 
Yes, it does.
But it warns me that doing so will erase information that a technician will need to see.
I am hoping you guys will tell me if this is something I should have addressed or if I can ignore it.
 
The ECU is going to use that sensor to determine how fast the output side of the transmission is turning in order to understand how and when to shift the transmission.  The sensor itself should be located on the top of the transmission towards the tail, and shouldn't be a terribly expensive thing to replace.  But before you do so, understand that the computer isn't telling you that the sensor is faulty - only that the data coming from the sensor isn't what it is expecting.  There could be something else going on with the electrical system that is generating noise and throwing things off or there could be a wire that has rubbed up against something and become compromised.  If the transmission appears to be shifting the way it normally shifts, then it could be a transient problem.  If, however, it hangs a bit before a shift, shifts too early, or shifts particularly hard, then whatever the fault is should be a little bit easier to find since there's something actually broken that can be tested for.  You'll know that things are really in need of investigation when the "overdrive off" light starts blinking.

Since you say that the coach is driving okay, I would go ahead and clear the codes with the scanner.  If there's really a problem, the code will come back and further troubleshooting can continue unhindered.  If the light comes back on, then the sensor can be tested to see if it's at fault or if there's some other electrical gremlin.  On some installations, Ford ran the harness from the transmission to a connector to the main ECU harness and that connection point can introduce intermittent issues (rare, but possible).  I've seen alternators spitting out bad power cause sensors to act a little weird, and I think there's even a TSB out there that involves the coil-on-plug system.  And, of course, it's entirely possible that you've failed that sensor itself.
 
mudshark said:
Yes, it does.
But it warns me that doing so will erase information that a technician will need to see.
I am hoping you guys will tell me if this is something I should have addressed or if I can ignore it.

Resetting and waiting to see if the code comes back is a standard diagnostic tool to eliminate occasional fluke alerts. If the problem is permanent and not just a temporary condition, the SES light will come on again, usually within a short time of heading down the road in this case. Disconnecting the battery and multiple restarts have the same reset effect as the erase function.
 
Thanks Guys
The "Overdrive Off" light was blinking for a short time. I don't know how long it was blinking cause I noticed it shortly before I shut down at a stop. When I started up again it was out. I thought that was peculiar. Didn't happen again. I remembered when wae brought it up. How serous
is this?
 
The blinking OD light just indicates that the SES light is being set by a transmission related sensor issue, and we already knew that from the code readout. Wait and see if either event occurs again before taking any further action. As said, if it's the output speed sensor, it's not a big deal to change.
 
Thanks NY_Dutch
We are here until 7/5. I think I will use the code reader to reset the warning light. I don't think it in our best interest to disconnect the chassis battery at this time. Should be easier to just use the code reader. Will post again if the problem resurfaces when we move again.
 
Used the code reader to cancel the warning light.
Won't be back on the road until 7/6. Will let you guys know how we make out.
 
I have found that the output speed sensor on pickups and cars will leak internally and cause fluid to fill the connector up and cause a code for output speed sensor. Check the wiring to the sensor to see if it has rubbed on something and shorted and unplug it and see if fluid is in connector.
 
I will try to crawl under the bus today before the heat hits 90.
What am I looking for? What does it look like?
 
Morning All
We arrived at our next destination, a mere 28 miles from our last stop. The warning light stayed off the entire way until we were backing into our site. Then it came on again with the overdrive light blinking. Anyone have a picture of what I should be looking at?
 
2011-07-26_021041_excursion_trans.gif


If that image shows up, you're looking for the sensor that is indicated by the right arrow.
 

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Thanks wae!
Do I replace both of them? Or just the one on the output end?
 
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