Help! ABS light on. speedometer jumping..
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Freshman User
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Help! ABS light on. speedometer jumping..
Hi,
My truck: 1995 Ford F150 4x4 4.9L XLT
ABS light is on..and the speedometer is jumping up and down.
I hear about a sensor..which is the correct sensor in my truck?
thanks
Luis
My truck: 1995 Ford F150 4x4 4.9L XLT
ABS light is on..and the speedometer is jumping up and down.
I hear about a sensor..which is the correct sensor in my truck?
thanks
Luis
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Joined: Sep 2008
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Look at the VSS (Vehicle Speed Sensor). If you look on the top of your rear differential, you should see an electrical connection, that will be the VSS. Remove and replace that. When you take the old one out, part of it can become stuck in the differential. That happened to me, took a bit of work to get it out so be careful.
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From: Noblesville,IN
Check to make sure the sensor connector's wires aren't rubbing on anything like shocks, sway bars, or the axle housing. FWIW the sensor from Ford fits the best. One from Advance looks the same but is a bit big for the sensor hole. the Autozone one doesn't look anything like the original or the others but fits ok. Ford also sells a pigtail connector in case yours is trashed.
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well you tried the cheapest fix so far. you might have a combination of problems. the only other reason why I know the ABS light would be on is either a problem with the ABS module (usually mounted on the frame rail) or a fuse for the ABS. you should be able to get the codes from the computer, that might help. Could also be a poor ground connection for the ABS circuit.
The other issue might be the PSOM (programmable speed odometer module). I had the same problem (jumpy speedometer). I found there were some electrical components on the back (capacitors and an IC) that were losing their connections and causing this. Luckily I have a friend who was able to solder things back on for me, but you might not have that and need to get a new PSOM.
Hope this helps.
The other issue might be the PSOM (programmable speed odometer module). I had the same problem (jumpy speedometer). I found there were some electrical components on the back (capacitors and an IC) that were losing their connections and causing this. Luckily I have a friend who was able to solder things back on for me, but you might not have that and need to get a new PSOM.
Hope this helps.
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Hi Rikil
Where the PSOM is located?, do you have a picture?
is normal to feel some pulsation or resitance in the break pedal at low speed in dry road ( 15 or 20 mph) ??
(adittional info, the digital odometer always have been working OK)
1995 Ford F150 4x4 4.9L XLT
Where the PSOM is located?, do you have a picture?
is normal to feel some pulsation or resitance in the break pedal at low speed in dry road ( 15 or 20 mph) ??
(adittional info, the digital odometer always have been working OK)
1995 Ford F150 4x4 4.9L XLT
Posting Guru
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The PSOM is located behind the speedometer, it is what controls the speedometer and the mileage. You need to remove your instrument panel to see it, once you do you will know exactly what it is. I thought I had a pic but apparently I don't.
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I´d like your opinion about my ABS comment..
on the other hand..if the odometer (mileage ) is ok.. and the speedometer is jumping, do you think the PSOM is the responsible?
thanks
Luis
on the other hand..if the odometer (mileage ) is ok.. and the speedometer is jumping, do you think the PSOM is the responsible?
thanks
Luis
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Senior User
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From: N.B., Canada
I have the same truck and the same problem. It's likely that the ABS module is confused by the speedometer readings changing so much. I found that the ABS system would trigger way before my wheels were coming close to locking and found that to be a concern and have removed the fuse. So I have no anti-lock brakes till I sort out the problem but at least I can fully brake.
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Joined: Mar 2009
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From: N.B., Canada
It actually no longer jumps it just stays at zero. Luckily I got a manual tranny. Once it warms up around here I'm gonna sort out the problem. My first guess would be an electrical short as it only happens on bumps. The truck is lifted and the wires are probably at weird angles.
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in my case a capacitor fell off the circuit board, this was causing the speedo to jump all over the place. I heard these PSOMs were plagued with faulty soldering. As I was taking it apart another capacitor fell off and so did an integrated circuit (IC). As mentioned before, my friend soldered those on for me and it has been fine ever since.
If you do get your PSOM out, look around for a yellow/gold capacitor, about 1/4 the size of your thumb nail. It is small, definately. You'll have to know which way is up when it gets soldered back on, I may be able to help you with that. If you see more than one fall off, you will need to look at it under a magnifying glass to see what the numbers are on there because they aren't all the same and they need to be in specific places.
You can also order one off the internet and have them program it to your mileage, I think they cost about $250 and they make you sign a paper stating you aren't lying about the mileage they program in to it.
If you do get your PSOM out, look around for a yellow/gold capacitor, about 1/4 the size of your thumb nail. It is small, definately. You'll have to know which way is up when it gets soldered back on, I may be able to help you with that. If you see more than one fall off, you will need to look at it under a magnifying glass to see what the numbers are on there because they aren't all the same and they need to be in specific places.
You can also order one off the internet and have them program it to your mileage, I think they cost about $250 and they make you sign a paper stating you aren't lying about the mileage they program in to it.