A weird thing happened the other day. While I was driving my truck, it suddenly felt like it was going to stall, then it kind of sputter. I noticed that the overdrive OFF light started flashing and the truck ran kind of rough. I pulled over and shut the truck off and restarted it. Problem solved for a few hours anyway. When I got close to home it started doing it again.

Recent problems that I noticed before the OD off light started flashing...
The trans seemed like it didn't want to down shift under heavy acceleration.

When I passed signs that have built in radar, they showed me to be going a lot slower then my speedo said I was going.

To test my speedo, I drove a mile section of road with my cruise set at 60 and it took around 62 - 63 seconds to go around one mile. My tire size matches the size on the door post. This let me know that I had speed sensor issues.

I changed out both speed sensors in the 4R100 and this seemed to clear up the problem. The trans is shifting a lot smoother now.

I am so glad that I changed out those sensors. It was a challenge because I couldn't see the rear one and the front one is in a really tight spot.

BBD

 

Neither sensor on the transmission has anything to do with the speedometer.

 

Mark,

Thank you. Your knowledge and willingness to help is always appreciated.

I have to say that my transmission is shifting so much smoother after replacing those sensors.

Big Black Dually

 

I believe the speed sensor on the top of the rear end can cause the OD light to flash when it has issues as well. Sometimes you just need to remove it and clean the end. So if you have any more issues with it, take a look at that sensor.

 

What Chipworkz said. That one fixed my problem as well. The one on the axle.

 

Have you checked the accuracy of the speedometer after your fix? The two sensors you changed won't affect the speedometer.

 

I have not had a chance to check it yet, but it is shifting so much smoother after changing them both on the 4R100.

Are there other one I can change out as well?

Thanks guys,

BBD

 

Have you checked for DTC for the Transmission? If the TCIL was flashing, a DTC should be stored in the PCM.

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

TRANSMISSION CONTROL INDICATOR LAMP (TCIL):

1. Flashing TCIL

2. Diagnostic Tools Required: OBD-II On-Board Diagnostics, Phase 2 Vehicle Media Communications Unit (Scanner - PWM Capable) / Pressure Gauge, Line, and Fitting / DVOM

3. A Flashing TCIL is an indication the Transmissions electronic circuit has identified an anomaly in its operation.

4. It will be necessary to read the Diagnostic Trouble Codes to identify the specific code(s) which have been stored to assist in diagnosing the trouble (P-102 - P1783 Fault Code Identification Chart).

5. Testing:

a. DTC Fault Code Retrieval

b. Circuit Monitoring

c. Circuit Integrity

d. Pump Pressure

*** Driving the vehicle may cause damage.

 

Thanks Pirschwagon,

That is important information to know.

I stopped by a NAPA autoparts today and asked if they would scan my truck.

Their scanner showed.. No DTC stored.

I am thinking that I may have erased any stored codes when I removed and swapped the batteries on Sunday while I installed an AIS.

I may get it scanned in a few weeks to see if any codes have popped up.

Thanks again for your help.

Big Black Dually

 

You did clear the codes by changing the batteries.

But even if you didn't, chances are NAPA would have still told you there were no codes. I haven't found an auto parts store that uses the right scanner to read Ford transmission codes. Even if the codes are there, they won't be able to see them.

 

Like Mark said, my normal scanner won't show the Transmission codes. To see those, I have to use my AutoEnginuity program.

AutoEnginuity Enhanced Ford Expansion - Riffraff Diesel Performance

 

Well I have had my share on "Blinking OD Light" problems so I'll share my experience on the subject. I have had to pull and clear the VSS on the rear diff, another time the diff sensor went bad I used a DVM and the ohms were wrong replaced the sensor. Next time I had a blinking OD I ended up replacing the plug that goes to the VSS on rear diff. I do not know what the code was that lead me to the rear diff. It was years ago. Twice the OD light starting blinking and the speedo was jumping around and it end up being the windshield was leaking and water was getting on the GEM unit. 1 other time the cab lights were leaking and water got on GEM causesd OD light blinking and speedo jumping around. Having the windshield R&I /resealed and R&I cab lights and seal along with pulling the GEM drying it out & pins cleaned cured it. So far that is 6 times I had issues with blinking OD.

The worst problem I had with a blinking OD light was the retaining ring in the trans that holds the OD clutch pack together with IM came off. The factory retaining ring was know to do that. There is an upgraded OD spiral retaining ring made by Sonnax. Cure for that was total rebuild of trans & TC.

Now I see you too have a DRW so as far as speedo goes I run stock LT235/85R16 and my speedo reads if I recall correctly 4 or 5 mph slower than actual speed. This is per speed traps and GPS. Something I have learned to live with.

 

Ed, if you have access to AE you can change programmed tire size and fix that problem. If you're coming through Atlanta any time soon we'll make sure to make that meeting happen and I'll bring my AE.

 

Thanks for that.

I will have to get this scanned somewhere else to see if a different scanner can find codes.

I think my speedo does the oppsite. It might show that I am doing 50 but the speed sign shows much slower.

I live in the far west suburbs of Chicago if anyone knows a shop that could help..

Thanks

BBD

 

I know a good shop in Joliet. How far is that from you?