2001 F150 Harley - 5.4 V8 with e40d
-KB blower kit and chip have been on it for years from prior owner

Speedometer troubleshooting - needle pegged after jump start!
Short story long, all other gauges work on the dash, but the speedo is pegged all the way to the limit stop (past 100mph) when sitting in the driveway at idle.

Any suggestions to troubleshoot/resolve this? I have some thoughts but was hoping someone else might have run into this and appreciate any insight. i.e.

• dash display mechanical or elecrical?
• speedo gear in transmission case (e40d)
• fuse blown for separate trans / speedo circuit?

Note: all the other gauges seem to read fine, RPM, oil, coolant, etc, etc.
Note: even with the engine off, key removed from ignition switch, speedo is still pegged!
Potential cause: jump start?

It was a very cold morning here (&the battery must have been a bit low); when cranking the engine over, the truck almost started, but I could hear the cranking slow from low voltage. So instead of cranking and further draining the battery I used my wall charger to jump it. It has a 15-amp start mode, and the truck started right up on that setting.
Problem is I don't know if the speedo was like that before I had jump started it, the truck has been sitting for some time.
Speedo is now pegged all the time, I tried driving reverse and forward low speed in the driveway. I reset the trip meter on the LCD below the speedo (button on speedo). Nothing seems to move the needle.
The O.D button on the tip of the shifter works, and the "o.d." indicator illuminates at the end of the shifter stalk.
To me it seems strange that the whole dash works except the speedo, and second, if it were the speedo gear being stuck/stripped in the trans, that should not make it read high-speed. Maybe an open circuit to the VSS?
There is also a CEL, so maybe the computer is making the speedo read pegged..... because it has tripped a fault for loss of vss? But then I would expect it would return to zero with key off. (mechanical issue in the speedo needle/gear?)
The truck is just sitting and waiting for winter storage (storage insurance), so not driving it.
I was just starting it to move it a little and keep everything lubricated and didn't want to put it away and drive it much if the trans might malfunction with a real-speed input problem. I guess I just hate to leave it with a problem.
My old computer I had diagnostics on crashed so it will take me some hours of messing around trying to find software and registration codes to setup a new computer. So I appreciate any insight on this one.

Trying to fix it myself and between jobs so $$$ is tight after the holidays.

 

Part of the dash function is to sweep the gauges when the battery is low.
This is often an indication for low battery supply.
If you were to enter the dash diagnostics the first thing that gets tested is the ability of the gauges and digital display to function.
My feeling is the speedo needle is physically stuck full scale.
In the future, I would charge the battery instead of cranking off the charger.
You have a whole house full of electronics in your truck.
For storage, fully charge the battery then disconnect it otherwise it will drain over time because the PCM and some other devices are still taking power when just setting.
Good luck.

 

Thanks for your insight. Yeah, I figured out my diagnostic sw would not run on my win 8.1 computer, so I bought a $25 blue tooth adapter off amazon. Then downloaded the free version of the android app on my phone (torque).

I was able to check faults and clear them with that.

Good news is I don't think there is any problem with the VSS.
Bad news is that means tearing apart the dash, to see if the needle is mechanically stuck, and with any luck can simply be free'd up.

I have no faults related to anything in the driveline, the only faults I have are related to the engine.

Furthermore I pulled up a display of the OBD-based vehicle speed, and moved forward and backward and 5mph registered no issue, so it seems the speed sensors are reporting fine.

After I resolve that issue, which I hope is fixable without a dash display swap.... Then I'll have my work cut out for me on the remaining engine faults ....

I'm not sure which of the two middle cylinders on the drivers side bank are #6, but I believe it is the 3rd plug from the firewall.

P0135, P0306, P1131

A misfire #6 fault, (noticed a rough idle also) and have O2 sensor fault front, and a bank "1" lean fault. I thought bank one is the drivers side, matching the #6 cylinder, but based on a quick search I have found bank 1 is the passenger side. So they seem to be separate issues unless a vacuum leak or dirty maf could be contributing to all of them.

That will have to be the topic of a whole different thread,..I'll dig into that one and likely start a new thread regarding intelligent plan of action (diagnosis instead of throwing parts!). Maybe it will help someone else as well.

Best regards.

 

Hold the phone a bit.
First, bank 1 is the passenger side.
Cylinder count from front to rear 1.2.3.4.
Bank 2 is driver side front to rear.
Cylinders 5.6.7.8.
Cylinder 6 is second from the front on driver side.
.
Next, don't worry about the codes 135 and 1131.
They are a response to the missing cylinder only and will clear when the cylinder misfire is fixed.
Do not replace or work on the Ox sensors. they are not a trouble.
Good luck

 

More good news bad news, the battery is toast, and after attempting to restart it with a low battery the speedo jumped back down to zero! no dash dismantling required!!!!
apparently the failure just needed to be duplicated lol.

So going to leave her for winter and put a new battery in her in the spring and fix the misfire fault to start with..... I think it may be time to sell her after the misfire fix in the spring I just won't be using it that much anymore. Has a new ford lightning shortblock dealer installed since about 3 years ago with only maybe 30k miles on it (I can dig up the original reciept and giant dealer bill to get a more exact mileage); Full mangnaflow exhaust with new cat pipe stainless from headers back. Mostly new front suspension (i.e. upper control arms, new upper lower ball joints, tie rod ends, bushings, pitman, etc) Has performance rotors and pads and tires in good shape. Bilstein shocks on 4 corners. If anybody is interested hit me up in the spring.

 

If the truck is to set unused for a year or so treat the gas with STA-BIL additive otherwise you will have a new problem later on top of what you already have.
Mi ole gal is at 225k and still rolling good.
Good luck.

 

If you hold down the reset button and then turn ignition switch to the on position it will force sweep the guages try that before tearing dash apart

 

5+ year old necropost?

 

good to know..
didn't know that...havent needed it (thankfully)

necropost......lol