My truck started having issues with the speedometer working intermittently as I was driving and then the ABS Light would come on. After shutting the truck off and restarting, everything worked fine then the speedo would bounce causing the engine to hesitate everytime it went to 0, then the ABS light would come on again.
I searched the forum, and I changed out the VSS on the pumpkin. Same problem. Any other suggestions?
Did u check the third high mount brake light. When they go out cause problems similar to what u describe. Bad brake light switch will cause abs light to stay on also.
most likely it si the wiring to the VVS, check about the last 10-13 feet of the harness, you may have to cut it open, you should find a spot that was nicked years ago and is now corroded, pretty common problem really.
__________________ Sold to JCart , 1997 F250 FireTruck Red,CC SB,auto( Presicion TC, HD-2Tugger),5" exhaust, Swamp 140cc injectors, TWildman 4-pos chip,open air cleaner, I/C w Banks intake, ,AIC,dual electric fans,Sky mfg RSK w/ D60w/ARB locker,she's well taken care of now pictures
2004 Dodge 3500 twin turbo 525hp rocket
Intermittent ABS light and Speedometer Fluctuation
I had a similar problem, swapped out the sensor on the differential. Found significant metal attached. 100,000 mi worth. Differential and tone ring were fine fortunately..TG. No codes were being recorded but problem continued. Finally gave the dealer a try. They were stumped as well. They ended up seeking advice from Ford Engineering.
Unbelievably, it turned out to be a faulty ignition coil on #8 cylinder emitting radio frequency interference to the electrical system and triggering the ABS module.
I have changed the Speed Sensor, i have inspected the wiring under the bed, the center brake light works. The speedometer is still intermittent, most of the time now as soon as you get near 40mph it will become erratic bouncing from 10 to 50mph and then the transmission will attempt to shift to match what it thinks the speed is. if it ever makes it all the way down to zero it will trip a transmission error wich starts the hard shifts. what is left? does the signal from the speed sensor feed the speedometer or the computer? could this be a computer problem? Is there any thing else that can cause this?
The VSS feeds both the speedo and the PCM. Next thing to check is the tone ring (aka reluctor ring) in the diff. It's mounted on the diff gear, and the sensor basically counts the teeth on the ring as it goes around. If there's crud between the teeth, or the fluid is old and, er, gunky and leaving stuff on the teeth, or if there are damaged teeth, it'll do stuff like this.
if its not any of the easy stuff above, or what NIT mentioned....... there is a little bugger that is part of speedometer it self, designated the PSOM..... it causes the fluctuations on the guage and messes up everything even the trans if its an auto...... you have to replace the guage cluster if its this. ( been there with most everthing mentioned above)
so can't see if you have auto trans in sig, but if it get bad enough you could be doing hyway speed and the then it decides you should be in 2nd gear and not OD....so if you have an auto get to the bottom of it asap.
__________________
1995 F-250 PSD 4X4 EXTRACAB LONG BOX AUTO
TYMAR FILTER, 4" MBRP STAINLESS TURBO TO TAIL
EOT MOD FOR COLD STARTS
CUSTOM RUNNING BOARDS
SD STARTER
STANDENS FULL 3 LEAF FRONT SPRINGS
1990 25th Anniversary 5.0 GT
When my LSD died, I removed the connector from the speed sensor on the pumpkin. After the repair, the speedometer would bounce when it was over 45mph. New tone ring, new sensor... nothing helped. I plan on getting a new connector that attaches to the sensor, since those apparently can go bad. If the speed varies too much, then cruise goes away, and I get the ABS light.
You can get a new connector with pigtail for the VSS. The wires have to be soldered to get an adequate connection.
i had this problem on a 93 f 350 and the bearing on the right side of the ring gear went south and in doing so it ate up the speed sensor on the diff.
worth a look, if your lucky its is iron filings on the speed sensor
__________________ 1997 F 350 4X4, idm mod, wide open performance GQSSB turbo, stage 2` s by bean` s, intercooler, 4" no muffler, stack, trans from brians truck shop rear, disk brakes, and a stecher stage 1 hpop 6 position chip with bean` s programs crane valae springs, air dog lift pump and electric fuel pump and regulatorand water methonal injection
I had the same problem on my wife`s 95 f350 4x4 psd cc,
Had to remove the cluster assembly and have it rebuilt, fixed the problem.
You could also get a used cluster aseembly from a f250 or f350 psd.
__________________ 1995 PSD F-350 4X4 97 motor installed.
I found where the wiring to the speed sensor in the last foot of the loom had
rubbed through the insulation and corroded, but would make occasional contact
on the road bumps. I also had to buy a new plug for the reverse light switch
on the ZF-5 due to the terminals going bad in the original plug.
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Intermittent ABS light and Speedometer Fluctuation
Linear Mode
