psom and code 29
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Tuned
Joined: Mar 2001
Posts: 491
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From: MS.
psom and code 29
can a bad psom cause a 29.i keep getting a 29(insufficent input from vss) i have installed a new vss and connector and checked wiring. i noticed in a wiring diagram that the vss connects to the psom and the rabs module.
my speedo is steady,good tach,odometer is fine i dont think its the psom but stranger things have happened
my speedo is steady,good tach,odometer is fine i dont think its the psom but stranger things have happened
Post Fiend
Joined: Nov 2004
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From: Manitoba
The PSOM (Programabler Speedometer/Odometer Module) recieves a speed signal from the RABS/VSS sensor and using a programmed conversion constant, converts it to the standard 8000 pulses per mile vehicle speed signal. The PCM uses this speed signal and other inputs to determine the proper trans line pressure, shift schedule and convertor clutch control.
If you have over/under sized tires and have not adjusted the system then the PSOM is sending bad info to PCM. Other than that check all connections or change the PSOM if you feel it's the bad boy.
If you have over/under sized tires and have not adjusted the system then the PSOM is sending bad info to PCM. Other than that check all connections or change the PSOM if you feel it's the bad boy.
Thread Starter
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Tuned
Joined: Mar 2001
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From: MS.
i disconnected the rabs module as i was having brake problems anyway.it seems to shift better.trying to figure out how thats possible unless the speedo sends the signal to the rabs and then to the pcm for analysis
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Tuned
Joined: Mar 2001
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From: MS.
92 f350 7.3 e40d,this truck is killing me i keep getting a constant 29 in the hard codes. took out the vss and put a brand new one in.i applied voltage to the ltgr/bl & red/pk wire from the vss and verified voltage @the speedo connector.i thought pulling the rabs helped but i was wrong.when driving i can go through the upshift fine.but sometimes during downshift when i reach 1st and try to reaccelerate,it dosent want to reshift 2nd(light dosent always flash)until it reaches 3rd.however if i decelerate to 15 mph or stop it upshifts perfect.occasionally if i accelerate hard when it reaches od it will shift hard and the light will come on and set hard code 62 tcs. code 29 is always the first code. i think 29 sets first and is causing the 62.any ideas this truck is my money maker.i gotta figure it out. ive been to the ford dealer guess what they told me."get rid of the truck there is no way you will figure out whats wrong".the transmission shop shake thre heads and run when they see me coming
Post Fiend
Joined: Nov 2004
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From: Manitoba
My reading material states check all the connections on the trans, with special attention to the one on the pax side with the heat shield. R&R the shield when checking that connector. To remove the connector press down on the center tab and pull up on the wire harness, do not attempt to pry the tab with a screwdriver. Any dirt/corrosion/bent pins, water, missing or damaged seals etc etc will cause a multitude of problems.
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Tuned
Joined: Mar 2001
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From: MS.
thanks for the help ,the trucks been making a awful noise shifting between 3-4 & 4-od swear it sounded like driveshaftso i changed all the ujoints and hanger bearing but it kept doing it.well i keep pulling the vss and finding litlle shavings on it.i clean it put it back in it shifts good for a few miles.then starts missing shifts etc;well i just put this rearend in and i dont think the gears are set right cause when i pulled the pan found metal particals(micro)mixed in the oil and this could cause that noise when shifting looks like the pinnion is hitting the carrier as there are gouges that match the pinion around the carrier. to make a long story short is this the cause of the vss not sending the psom the right info? if so now i gotta figure how to set these gears.ive never set up rear gears before its a 10.25
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Post Fiend
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Tuned
Joined: Oct 2004
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I think it will be in the top of the rear diff housing.
a psom can indeed cause such trouble. I was at the shop I used to work at and my former cowoker was telling me about a F350 with an E4OD that had recived a new tranny (Jasper, at another shop) but still shifted so hard it chirped the tires. It was not setting any codes, but after some careful searching he found the trouble was the PSOM. He put a new one in and the trouble was solved
a psom can indeed cause such trouble. I was at the shop I used to work at and my former cowoker was telling me about a F350 with an E4OD that had recived a new tranny (Jasper, at another shop) but still shifted so hard it chirped the tires. It was not setting any codes, but after some careful searching he found the trouble was the PSOM. He put a new one in and the trouble was solved
Tuned
Joined: Oct 2004
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I do not really know for sure, but I belive it is intergrated into the speedomater in the dash, i.e. the instrument cluster.
P.S.
If your truck is a 99F350 you should probably try the correct forum, as this one is focused on the pre-powerstrokes (1994 and prior).
good luck
P.S.
If your truck is a 99F350 you should probably try the correct forum, as this one is focused on the pre-powerstrokes (1994 and prior).
good luck