VSS question on 92 E350
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From: lafayette tn
VSS question on 92 E350
I've listed my problems over in the diesel forum for a while, I have a E4od that is locking and unlocking the torque converter at 40mph. I checked the voltage specs on the vss and they are way out of wack, but the speedometer is accurate. I didn't know if the speedo is driven off the vss or still off the tail of the tranny housing on this model (it's at the shop and I want to find out before ordering a new vss). Tranny is freshly rebuilt and this problem was there before the old one blew up, and it tests fine with a seperate tranny control box. Been at the shop for a few weeks now and no one can figure it out.
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On my 95 E-150 5.8 4EOD I had the issue of OD on and off, before and after transm overhaul. After the overhaul (OD continued to turn off) I read diagnostics and found VSS code. Replaced the VSS, however problem came back. Then I found a bad wire at the harness somewhere close to the rear axle. OD problem went away. During all this time Speedometer worked fine.
VSS is really a combo VSS / ABS Speed Sensor located in the rear axle (Diff). According to the Ford literature Speedo Module gets is signal from this sensor. Its a mystery to me that while the VSS had a circuitry problem, the speedometer worked fine.
I am not sure on this one -- but I gotta think that maybe there is a correction that happens somewhere, maybe from the input of the Transmission Output Shaft Sensor (OSS)? Maybe Speedo Module reads VSS input, asks PCM "how is your OSS reading", they communicate and establish that VSS is whacky and say "let's use the OSS"? Bottom line, PCM needs a reliable input in order to control many important things that are speed related. But I could be wrong..
VSS is really a combo VSS / ABS Speed Sensor located in the rear axle (Diff). According to the Ford literature Speedo Module gets is signal from this sensor. Its a mystery to me that while the VSS had a circuitry problem, the speedometer worked fine.
I am not sure on this one -- but I gotta think that maybe there is a correction that happens somewhere, maybe from the input of the Transmission Output Shaft Sensor (OSS)? Maybe Speedo Module reads VSS input, asks PCM "how is your OSS reading", they communicate and establish that VSS is whacky and say "let's use the OSS"? Bottom line, PCM needs a reliable input in order to control many important things that are speed related. But I could be wrong..
Fleet Owner
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From: Reynoldsburg, Ohio
Henry like you I was under the impression the VSS feeds the speedo as well as the cruise control module if so equipped---that part makes total sense. I'm not sure of the OSS would be in conjunction with the VSS but that's my guess only and not to be taken as fact at all. I'm thinking if the rear wheels are slipping like loss of straight line traction on ice the speedo registers wheel speed. If allowed to accelerate the tranny would eventually shift into the next higher gear, perhaps as a function of the VSS and OSS communicating with the PCM, thinking there was forward motion?
I do know from experience the wrong speedo head on '96's and above does affect the tranny to the point it won't shift at all without the circuitry in the speedo head. Suffice it to say a 2003 diesel speedo will NOT work worth a hoot in a '97 E250 with 5.4 gas motor!
I do know from experience the wrong speedo head on '96's and above does affect the tranny to the point it won't shift at all without the circuitry in the speedo head. Suffice it to say a 2003 diesel speedo will NOT work worth a hoot in a '97 E250 with 5.4 gas motor!
Frmr Ford Trans Engr
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From: SE Florida
E4ODs do not have an OSS.
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From: lafayette tn
well, week 4 and still not fixed! I went up to the shop myself and crawled under this enormous beast and saw that the vss is on the rear differencial, so speedo is electronic and doesn't sound like it will fix the problem at 40mph.
I did look at the wiring going into the harness that feeds the tranny, and I saw the red/white wire was pretty messed up with some of the insulation off of it, and the grey wire had some type of splice with a resistor that had one of the two wires cut off. I asked the tranny shop guys about the resistor and the one who first looked at it said he cut one of the lines so that they could accuratly test it.
What are the chances that fixing these two wires will fix my converter lock up issue at 40 mph. This is the only speed that it does this thing at but, I do a lot of driving in town and it gets irritating and it can't be good on the converter.
Anybody have specs on what these two wires are for?
I did look at the wiring going into the harness that feeds the tranny, and I saw the red/white wire was pretty messed up with some of the insulation off of it, and the grey wire had some type of splice with a resistor that had one of the two wires cut off. I asked the tranny shop guys about the resistor and the one who first looked at it said he cut one of the lines so that they could accuratly test it.
What are the chances that fixing these two wires will fix my converter lock up issue at 40 mph. This is the only speed that it does this thing at but, I do a lot of driving in town and it gets irritating and it can't be good on the converter.
Anybody have specs on what these two wires are for?
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From: NY, NY
It might be a lot of stuff on this board for the E4OD. I will be back home tomorrow and can check these wires on my CD Wiring Diagram. Reading through the following links, it seems that any bad wire would definitely spook something...
Did you check the wiring for the VSS for any physical damage?
FullSizeBronco.com - 78 - 96 Ford Bronco offroad club, forums, tech, installs. Someone was actually talking about eliminating the converter lockup (the opposite) by cutting the pin that grounds the Converter Lockup Clutch solenoid
This a link the blow-up diagram for the E4OD beast 1983 Ford Bronco Diagrams picture | SuperMotors.net.
There are guys on this board that know a lot more about transm that might be able to provide the correct info...
Did you check the wiring for the VSS for any physical damage?
FullSizeBronco.com - 78 - 96 Ford Bronco offroad club, forums, tech, installs. Someone was actually talking about eliminating the converter lockup (the opposite) by cutting the pin that grounds the Converter Lockup Clutch solenoid
This a link the blow-up diagram for the E4OD beast 1983 Ford Bronco Diagrams picture | SuperMotors.net.
There are guys on this board that know a lot more about transm that might be able to provide the correct info...
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From: NY, NY
I did look at the wiring diagram on the CD for my 95 E-150, and and I did not see any wires with the colors you mentioned.
This on both connectors at the transmission: Main connector and TR (transmission range sensor). Maybe your "92 E-350 has different wiring (unlikely).
This on both connectors at the transmission: Main connector and TR (transmission range sensor). Maybe your "92 E-350 has different wiring (unlikely).
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From: lafayette tn
my colors were off on the tranny but it turned out to be a bad vss from the store? Couple that with the rpm sensor going bad on the diesel, the new tranny didn't know what to do! Thanks for the reply ya'll, I've had quite the eductaion lately!
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From: lafayette tn
just a guess here but either they gave me the wrong model vss (entirely possible since their computer system listed 4, one of which was for the tailshaft of the tranny?) and they have slightly different specs or it was just out of range of ford's specs...kinda not built right kind of thing. Come to think about it, I never did check the accuracy of the speedo against my gps; so it could have been off but consistantly progressive. The old one that is back in right now is dead on according to the gps systems I have (first vehicle I've ever owned that was right on...and I've owned quite a few)
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