95 f150 speedometer problem
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From: Montana
95 f150 speedometer problem
So, I backed up and hit a curb with some force, nothing extreme but did give a little bit of a bump. Now my speedometer is freaking out at all speeds, from 0-75? im guessing (i dont exceed 75 ever) the needle flies around, will go from the 70 mark all the way past the last mark (85) and back, and i am not sure what is causing it. I bought the truck 2 weeks ago, has 104k, the two previous owners were older so the truck was never hot rodded, and has towed/hauled minimal stuff. The speedometer worked fine earlier today, and worked sense I bought the truck. I saw someone say it was the VSS, another said PSOM but my symptoms are different then both of theirs. Odometer works fine, abs light isnt on. Any help?
Fleet Owner
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From: Easton,Ks
I am not sure what you are saying.
Are you saying the needle will bounce from zero to 75 and then back to zero and sometimes 85+ when you a going say a steady 55mph?
If so my guess would be you dislodged the tone ring in the rear end.
The only way to be sure is to put a scope at the RABS test point plug at the hood hinge drivers side and run speed to about 30mph up with the rear end up on jack stands.
You should see a steady wave form at about 667Hz with the RABS module unplugged. If not you have a problem in the rear end.
If you DO NOT have a jumpy wave form then you have a problem with the PSOM or the speedometer head.
If no scope you can get a speedometer head and PSOM from a salvage yard and put it in your cluster for a test. The whole cluster with the speedometer head and PSOM are only $26.99 at a salvage yard. That is what I pay for them at pick & pull. There is a Environmental Fee of $2.19 and Local Tax on the item also.
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Are you saying the needle will bounce from zero to 75 and then back to zero and sometimes 85+ when you a going say a steady 55mph?
If so my guess would be you dislodged the tone ring in the rear end.
The only way to be sure is to put a scope at the RABS test point plug at the hood hinge drivers side and run speed to about 30mph up with the rear end up on jack stands.
You should see a steady wave form at about 667Hz with the RABS module unplugged. If not you have a problem in the rear end.
If you DO NOT have a jumpy wave form then you have a problem with the PSOM or the speedometer head.
If no scope you can get a speedometer head and PSOM from a salvage yard and put it in your cluster for a test. The whole cluster with the speedometer head and PSOM are only $26.99 at a salvage yard. That is what I pay for them at pick & pull. There is a Environmental Fee of $2.19 and Local Tax on the item also.
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So, I backed up and hit a curb with some force, nothing extreme but did give a little bit of a bump. Now my speedometer is freaking out at all speeds, from 0-75? im guessing (i dont exceed 75 ever) the needle flies around, will go from the 70 mark all the way past the last mark (85) and back, and i am not sure what is causing it. I bought the truck 2 weeks ago, has 104k, the two previous owners were older so the truck was never hot rodded, and has towed/hauled minimal stuff. The speedometer worked fine earlier today, and worked sense I bought the truck. I saw someone say it was the VSS, another said PSOM but my symptoms are different then both of theirs. Odometer works fine, abs light isnt on. Any help?
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From: Montana
Update:
Sorry about the confusion, I meant to get across that that needle will be bouncing from any speed inbetween 0-75, whenever im driving. I GPSed it today, and the needle seems to only bounce higher then the speed I am actually going. I think there might be a lose wire though or something because after crossing cattle guards it started working again, but after a small road bump started bouncing again. Someone who had a similar problem had the rear end go out and the same speedometer problem, but not 100% sure. Cleaned the VSS? or PSOM whatever is plugged into the rear axle but that did nothing.
Sorry about the confusion, I meant to get across that that needle will be bouncing from any speed inbetween 0-75, whenever im driving. I GPSed it today, and the needle seems to only bounce higher then the speed I am actually going. I think there might be a lose wire though or something because after crossing cattle guards it started working again, but after a small road bump started bouncing again. Someone who had a similar problem had the rear end go out and the same speedometer problem, but not 100% sure. Cleaned the VSS? or PSOM whatever is plugged into the rear axle but that did nothing.
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The thing plugged into the rear axle is the VSS. It is possible the connector is loose. The connector has a clip on each side. When I replaced mine one side broke so I zip tied it back. Just a thought. Look on top of your rear end
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PSOM issue
Okay, so first off. I want to apologize for hijacking this thread. But I am new to the forum and not entirely sure how to post new threads while using my work computer (it does not load certain images and buttons). But basically here's the jist. I have a 1995 Ford F350 with the ZF5 and 7.3 Powerstroke and it's a two wheel drive with single rear wheels. I'm suspecting this rear end is not original as I don't believe they ever made the crew cab, long bed, 2wd with just single rear wheels.
But anywho. My speedometer and odometer does not work. RPM, and all the other gauges do. The odometer just reads mileage but does not reset, does not register new mileage and the odometer simple twitches upon ''key-on'' position. I went and took the rear diff sensor out but the one provided to me by autozone does not look like the one in my diff, the rear diff sensor looks more like an abs sensor as opposed to a VSS.
Could anyone help me explain what's wrong?
But anywho. My speedometer and odometer does not work. RPM, and all the other gauges do. The odometer just reads mileage but does not reset, does not register new mileage and the odometer simple twitches upon ''key-on'' position. I went and took the rear diff sensor out but the one provided to me by autozone does not look like the one in my diff, the rear diff sensor looks more like an abs sensor as opposed to a VSS.
Could anyone help me explain what's wrong?
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From: Easton,Ks
Thebus1995,
The rear end sensor very seldom goes bad but it does get replaced a lot.
The rear end sensor is both the VSS & the RAB sensor.
When you say "odometer simple twitches upon ''key-on'' position" sounds like the one I had on the bench today. You could push on the PSOM chip and as you say the odometer twitches then it was blank again but I could get it to read once in a while by pushing on the corner of the chip. Then all of a sudden the big chip just fell off the board.
As RIKIL said above it sounds like a loose component.
The rear end sensor very seldom goes bad but it does get replaced a lot.
The rear end sensor is both the VSS & the RAB sensor.
When you say "odometer simple twitches upon ''key-on'' position" sounds like the one I had on the bench today. You could push on the PSOM chip and as you say the odometer twitches then it was blank again but I could get it to read once in a while by pushing on the corner of the chip. Then all of a sudden the big chip just fell off the board.
As RIKIL said above it sounds like a loose component.
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Well, really nothing happens when I push trip or reset. But when I first roll the key from off to ''on'' the dash does it's thing and the odometer twitches, but does not really do much else after I start the vehicle. I could check that tonight but I seem to only find threads based on the auto version of my truck, not the 1-ton five speed.
''Real trucks don't shift themselves'' lol, jk
''Real trucks don't shift themselves'' lol, jk
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Fleet Owner
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From: Easton,Ks
Gas and the 7.3L should use the same PSOM - Speedometer center in the cluster.
The tachometer is different but every thing else is the same in the cluster.
There are some different lamps that light with the diesel but the PSOM is the same and does output to your PCM Computer. What your PCM does with the information I do not know on a diesel with the ZF5.
So lets get back the the PSOM and the odometer.
The odometer should come on with a backward 6 and the rest 8's when the key is turned on and then go back out and then display the mileage of the truck. Is this what it does?
The tachometer is different but every thing else is the same in the cluster.
There are some different lamps that light with the diesel but the PSOM is the same and does output to your PCM Computer. What your PCM does with the information I do not know on a diesel with the ZF5.
So lets get back the the PSOM and the odometer.
The odometer should come on with a backward 6 and the rest 8's when the key is turned on and then go back out and then display the mileage of the truck. Is this what it does?
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Lol, unfortunately I used to be pretty tech savy when I was much younger, but now not so much. So any of the ''testing'' I would have to have broken down to Barney level detail. I cleaned the rear sensor off and stuck it back in because the weirdest thing. ABS does work. So I'm not sure what the cause could be. I may just have to tear into the cluster to see what's wrong, but I figured I would see if there's anything that I could do to diagnose what's going on as opposed to just throwing money at it.
Also, is there any procedure to rebuild these PSOM's? Again, everything I've researched is in relation to the Auto transmissions, not the stick. So it seems that my truck is unique in more than one way.
Also, is there any procedure to rebuild these PSOM's? Again, everything I've researched is in relation to the Auto transmissions, not the stick. So it seems that my truck is unique in more than one way.
Fleet Owner
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From: Easton,Ks
See if the speedometer will prove out and display information on the LCD readout.
Just hold in the reset button, the one on the left and then turn on the key. The pointer should go all the way to the right and peg and then go back to zero.
Release the button and the LCD should display information, then push the reset again and the LCD should display some more information.
Then turn off the key.
Turn the key back on and your mileage should display in the LCD.
Let me know if this works.
Just hold in the reset button, the one on the left and then turn on the key. The pointer should go all the way to the right and peg and then go back to zero.
Release the button and the LCD should display information, then push the reset again and the LCD should display some more information.
Then turn off the key.
Turn the key back on and your mileage should display in the LCD.
Let me know if this works.
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Okay, so I did that button test and the speedometer moved like you had stated it would, then where the mileage is typically listed it listed ''984CAL.'' Not really sure what this means. But I'm confident this is probably the first time in a long time the odometer's ever moved lol. This would lead me to wonder if the sensor, whereever or whatever it is is actually bad. But the weird thing is if the sensor would bad, wouldn't my ABS also not function? I was sliding down a slick slope the other day after it rained and the rear abs was working fine.
Fleet Owner
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From: Easton,Ks
The RABS yellow light is not on and the RABS system works fine.
Is this right?
Has anyone played with the wiring under the dash?
(between the RABS module and the PSOM)