2006 Ford Explorer 4.0 P0720 OSS Circuit Fault

Jordan Owner/Technician Washington Posted   Latest  
Resolved
Electrical
2006 Ford Explorer Eddie Bauer 4.0L (E) 5-spd (5R55S)
P0720 — Output Shaft Speed Sensor Circuit
Won't Shift

Pinned out the PCM harness connector to PIN 1-2 on the OSS. PIN 1 got reasonable ohms. PIN 2 open. Noticing the wiring diagrams, PIN 2 does not run back to the PCM but apparently runs to the O2 Sensors…?

I'm trying to chase a hard fault, assuming break in circuit somewhere. Both O2 Sensors appear undamaged. In “Explorer OSS Fault 2” image, can anyone tell me what “S106” is, and what the dotted line over to the O2 sensors is?

Just looking to see if I need to start cutting into the conduit off the harness by the PCM and tracing back.

Thanks everyone.

J.

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Chris Technical Support Specialist
New York
Chris
   

The other wire you are looking at is referenced as Signal Return. Ford uses isolated PCM supplied grounds for their sensors. S106 is Splice 106 that is located in the engine harness near the 'Take out" for C175 or where the PCM connector comes out of the main harness. diag​.​net/file/f1p23s8o4… ​ diag​.​net/file/f6etogsxm… ​

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Copyright
Glenn Owner/Technician
Texas
Glenn
 

S106 is a splice in the harness near the PCM it is yellow with a tracer and goes to the fuel charge harness. Go to the wiring diagram legend in your service information at the beginning and it will explains all the symbols and wiring identifiers.

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Santiago Owner/Technician
Texas
Santiago
 

Look at the transmission dip stick bracket, I had the same problem with before. The bracket did a very small cut to the output shaft signal enough to interrupt the signal.

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Jordan Owner/Technician
Washington
Jordan
 

I will explore around there, thank you. However, this vehicle has had the dipstick factory deleted it seems.

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Chris Technical Support Specialist
New York
Chris
 

Yes there is a standpipe in the middle of the drainplug to set the level.

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Timothy Owner/Technician
Wisconsin
Timothy
   

Signal Return is Fords way of showing a PCM supplied ground circuit. It's used for all sorts of sensors, from TPS to many others, including O2 sensors, etc. If you want to check if it's the issue, forget the ohmmeter and supply your own ground right to battery negative, you won't hurt anything. Or, you can just overlay a wire to the signal return at the PCM. Not too sure where Glenn got his…

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Jordan Owner/Technician
Washington
Jordan
 

Thank you. I can confirm the GRY/VIO. I'm going to find S106 and go from there.

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Jordan Owner/Technician
Washington
Jordan Update
   

Further Diagnostics resulted invalidating previous results of PIN2. I was able to get both continuity and .6-7 ohms off PIN2 and S106 when probed after gaining direct access to breakout harness. PIN1 when probed against PIN3 in C175T resulted in a continuity of .5-6 ohms. Further, my method for determining PIN2 Short to Ground was to Leave PIN2 probed, and then find a donor ground on the…

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Timothy Owner/Technician
Wisconsin
Timothy
 

Just run your own ground as I said. It won't hurt anything, and will eliminate the ground side as the issue, if it fixes it. It is just a ground. Don't over-think it.

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Jordan Owner/Technician
Washington
Jordan Resolution
   

Fiddling with all the wiring seemed to clear the fault code. Never found an actual failure point.

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