new to these trucks but more than wanting to learn ! p0720 code came up but want to check all electrical prior to replacing oss because problems seem to coincide with rough conditions ! OFFROAD ! bounce bounce bam bam ! well at least in the beginning and now constant under normal drive conditions ,tow haul warning flash lights up a block down the road and goes into limp mode ! what fuse protects the output speed sensor ? and or any other ideas ! have seen many post of people replacing sensor and still have the same code due to some harness ....problem ! thanks all :-jammi n

 

This doesn't list which fuse but does have some interesting/relavent info.

---------------------------------------------------------------

TSB 07-11-2

06/11/07

STUCK OR JUMPING / BOUNCING / ERRATIC SPEEDOMETER AND/OR TACHOMETER

FORD:
2005-2007 F-Super Duty

This article supersedes TSB 06-7-4 to update the vehicle model years.

ISSUE
Some 2005-2007 F-Super Duty vehicles may exhibit a speedometer and/or tachometer indicator issue. Symptoms may include intermittent, large inaccuracies, or jumping/bouncing/erratic pointers.

ACTION
Refer to the Service Procedure.

SERVICE PROCEDURE

1. Verify there are no diagnostic trouble codes (DTCs). If there are DTCs present, follow the appropriate procedure in the Workshop Manual to clear the DTC and resolve the concern.

2. Confirm that the axle ratio and tire size are properly configured in the ABS module.

3. For a speedometer related concern, If no DTCs are present, the issue may be with any of the following components:

^ Cluster

^ ABS Module

^ ABS Speed Sensor

^ Vehicle Wiring

^ If the symptom is a continuous (non-intermittent) large inaccuracy, ensure that the axle ratio and tire size are properly configured in the ABS module.



Cluster Concern

A known issue exists on the instrument cluster where it is possible for the graphics applique to separate from the cluster backplate and interfere with pointer operation. The suspect vehicle build months are July, 2005 to January, 2006. Although not impossible, vehicles built outside of this time period will likely not have this issue. The most common symptom is the speedometer pointer sticking while operating in cool or cold weather and the vehicle interior is beginning to warm up after a cold start. Revised instrument clusters are now available for service that includes a fix for this concern.

To identify the cluster as the root cause:

1. Monitor the vehicle speed sensor (VSS) PID in the powertrain control module (PCM), and the speedometer needle position while stopped.

2. If the speedometer displays 5 MPH (8 Km/h) or more, and the VSS PID indicates zero, replace the instrument cluster.

3. With an assistant observing the diagnostic tool, drive the vehicle at 20, 40, and 60 MPH (32, 64, and 97 Km/h) as indicated on the diagnostic tool, and record the value indicated by the speedometer.

4. If the speed indicated on the diagnostic tool versus speedometer readings vary by more than +/- 5 MPH, (8 Km/h) replace the instrument cluster.


ABS Module Concern

To identify if the ABS Module is the root cause, refer to diagnostic procedures in the Workshop Manual. For any customer complaints of jumping/bouncing/erratic speedometers, a wiring concern may exist which is severe enough to interrupt the signal, but not severe enough to totally open/short the circuit.




ABS Speed Sensor Connector Concerns

1. Inspect the ABS Speed Sensor connector on the 14405 harness for signs of water trapped in the strain relief elbow, corrosion, or connector broken/cracked. Install a new pigtail if necessary. Ensure that the harness is properly retained and routed to eliminate intermittent speed signals.

a. Disconnect the battery.

b. Disconnect the damaged connector from the axle.

c. Cut wiring near the rear wheel sensor takeout from the 14405 harness.

d. Splice in pigtail (pigtail includes heat shrink).

e. Cover heat shrink with tubing.

f. Route the two (2) retainers of the pigtail to park brake cable.

g. Plug in connector to rear wheel sensor.

h. Check for functionality.


2. Ensure that the harness is properly retained and routed to eliminate intermittent speed signals.

3. Add dielectric grease to the connector.


ABS Speed Sensor Concerns

To identify if the ABS Speed Sensor is the root cause, follow the diagnostics in Section 206-09:

Anti-Lock Control in the 2006 F-Super Duty 250-550 Workshop Manual, Diagnosis and Testing. If the pinpoint test states to replace the rear axle wheel speed sensor, replace with a new sensor.

Wiring Concerns

To identify if the vehicle wiring is the root cause:

1. Inspect the vehicle wiring for damage beginning at the rear wheel speed sensor connector and ending at the ABS module.

2. Damage may be at any point in the wiring. Inspect for pinched looms, frayed terminal connections, and loose pins.

3. Pay special attention to the wiring along the frame (especially if the vehicle has been modified from a body builder), and near the fuel tank.

4. The speed sensor wiring begins at the rear axle and is routed along the frame rail on the left side of the vehicle. It then branches off at C140 (gas C133) which is located beneath the master cylinder.

5. The wiring then goes to C455 at the ABS module.

6. Repair wiring as necessary.


Tachometer Concerns

For Tachometer related concerns, if no DTCs are present, monitor the tachometer (RPM) PID in the PCM, and the tachometer needle position while stopped and in park.

A known issue exists on the instrument cluster where it is possible for the graphics applique to separate from the cluster backplate and interfere with pointer operation. The suspect vehicle build months are July, 2005 to January, 2006. Although not impossible, vehicles built outside of this time period will likely not have this issue. The most common symptom is tachometer pointer sticking while operating in cool or cold weather, and the vehicle interior is beginning to warm up after a cold start. Revised instrument clusters are now available for service that includes a fix for this concern.

1. Rev the engine so the tachometer pointer reads 1000 RPM. If the tachometer (RPM) PID has a difference of more than 250 RPM than the pointer indication, replace the instrument cluster.

2. Repeat this process at 2000 RPM. If the tachometer accuracy passes this test, no repairs to the instrument cluster are necessary.

3. If the RPM PID in the PCM reads zero, or is noticeably erratic, inspect the engine RPM sensor, and associated wiring, to the PCM. Repair as necessary.

WARRANTY STATUS: Eligible Under Provisions Of New Vehicle Limited Warranty Coverage
IMPORTANT : Warranty coverage limits/policies are not altered by a TSB. Warranty coverage limits are determined by the identified causal part.

OPERATION DESCRIPTION TIME

MTO71102 Claim Additional Labor Actual
Required As Actual Time Time
Or Use SLTS Operation If
Available
DEALER CODING
CONDITION
BASIC PART NO. CODE
10849 42

 

sorry maybe in my ranting and raving I didn't explain myself well ! i have a transmission problem ! let me start from the beginning. started to feel a strange effect at low rpm's like a slip and a loud fan like sound , give it some throttle and would hook up and run normal . this went on for a week or so and I decided to drop the pan and check filters and oil (did not have obd2 reader at that time ). oil looks good and internal strainer clean . external filter was ugly (replaced) ! also unpluged oss and tss to inspect for corrosion (none found .refilled atf and ran . truck would go into limp mode in less than 1/4 mile . since then i have received my scanner and found the code p0720 present . if I disconnect batteries and clear system all good at low rpm's and jumps to tow haul warning as speed is applied, activating limp mode !

 

The fuse that protects the OSS is the same fuse that protects the PCM. If that fuse blows the PCM isn't powered and the truck doesn't run. I think we can eliminate that fuse as the cause of the problem.

I would suspect that there is a problem with the OSS connector or wiring to the OSS. It is also possible that the sensor is bad.

 

No, my bad. Went straight to the VSS when I read your post. Second screw up for me tonight.
I haven't replaced a OSS but tried to research a little and didn't find much consistent info.
A few post where the connector/wiring was damaged. It does seem the sensor is often the issue if the code is present.
The OSS connector is toward the bottom right on this print: https://www.ford-trucks.com/ford-man...%20diagram.pdf

Hopefully someone will post up some more specific (and helpful) info for you soon.

 

thank you Mark for your quick response ! as everyone does, I value your opinion
and can only hope for future support from someone who knows this system inside and out ! what is a pcm ? did I mention I was new to this ? on my trip down BAJA I had the turbo problems and found the black wire shorting to ground at the support on the turbo ! therefor I am gun shy when it comes to wiring ! I thought I should switch out the oss for the tss just to confirm . any opinion ?

 

thanks for the info . I always try to get as much info as possible before ordering parts due to the time it takes to get them ! in Mexico there is no next day mail service and I'm at the very end of the baja peninsula !

 

Powertrain Control Module, also known as the computer.

They are different parts and can't be swapped.