VSS Signals
Thread Starter
|
Postmaster
Joined: Aug 2001
Posts: 4,270
Likes: 5
From: Delaware
VSS Signals
I am trying to troubleshoot an E4OD that isn't shifting. I jacked up the rear of the truck, and ran the motor with the motor in gear. Then I looked at the +/- VSS Signals with an Oscilloscope. I saw some low amplitude pulses that I think are just noise.
What shouid the VSS Signals look like on a scope?
What shouid the VSS Signals look like on a scope?
FTE Legend
Joined: Jul 2005
Posts: 65,938
Likes: 1,432
From: Millersville, MD
It'll be in the tranny codes...unless you have the correct device to detect the tranny codes, you won't see it. It usually shows itself to the driver via a flashing overdrive light on the gearshift lever.
Thread Starter
|
Postmaster
Joined: Aug 2001
Posts: 4,270
Likes: 5
From: Delaware
It's not shifting into 3rd or OD. I put the VSS on a scope, but didn't see any signal. I need to know what the VSS signal looks like on a scope.
I can do the self test with the EEC-IV, and I have a LED to read the flashes. The self test passes.
I don't have a speedometer hooked up yet. I am going to check to see if the speedometer gear is rotating.
Moderator
Joined: Jan 2001
Posts: 56,977
Likes: 2,734
From: Virginia
Unplug your vss and then drive it. If you get the vss code in a memory code, then I would say it's ok. If you don't get any reaction from the computer, than I would be suspicious that something with it is not right.
This is a special EECIV computer that drives just the tranny like you said. It's a pretty good unit and is pretty good for troubleshooting. If it's working right, and is not getting a vss signal it can work with, it will set a code.
I am assuming you have some wiring diagrams? Have you hooked up a shifter stalk from a later truck? This will give you the ability to turn the OD on and off, and also has a light to flash any codes. If you don't have this, I would wire in some sort of substitute with a generic switch and light.
This is a special EECIV computer that drives just the tranny like you said. It's a pretty good unit and is pretty good for troubleshooting. If it's working right, and is not getting a vss signal it can work with, it will set a code.
I am assuming you have some wiring diagrams? Have you hooked up a shifter stalk from a later truck? This will give you the ability to turn the OD on and off, and also has a light to flash any codes. If you don't have this, I would wire in some sort of substitute with a generic switch and light.
Moderator
Joined: Jan 2001
Posts: 56,977
Likes: 2,734
From: Virginia
Trending Topics
Thread Starter
|
Postmaster
Joined: Aug 2001
Posts: 4,270
Likes: 5
From: Delaware
Unplug your vss and then drive it. If you get the vss code in a memory code, then I would say it's ok. If you don't get any reaction from the computer, than I would be suspicious that something with it is not right.
This is a special EECIV computer that drives just the tranny like you said. It's a pretty good unit and is pretty good for troubleshooting. If it's working right, and is not getting a vss signal it can work with, it will set a code.
I am assuming you have some wiring diagrams? Have you hooked up a shifter stalk from a later truck? This will give you the ability to turn the OD on and off, and also has a light to flash any codes. If you don't have this, I would wire in some sort of substitute with a generic switch and light.
This is a special EECIV computer that drives just the tranny like you said. It's a pretty good unit and is pretty good for troubleshooting. If it's working right, and is not getting a vss signal it can work with, it will set a code.
I am assuming you have some wiring diagrams? Have you hooked up a shifter stalk from a later truck? This will give you the ability to turn the OD on and off, and also has a light to flash any codes. If you don't have this, I would wire in some sort of substitute with a generic switch and light.
I will install a switch and LED for OD.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make
Brett Foote
Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!
Michael S. Palmer
Ford's 2001 Explorer Sportsman Concept Looks For a New Home
Verdad Gallardo
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
2026 Shelby F-150 Off-Road: Better Than a Raptor R?
Brett Foote
2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!
Michael S. Palmer
10 Most Surprising 2026 Ford Truck Features!
Joe Kucinski
Top 10 Ford Trucks Coming to Mecum Indy 2026
Brett Foote
5 Best / 5 Worst Ford Truck Wheels of All Time
Joe Kucinski
Moderator
Joined: Jan 2001
Posts: 56,977
Likes: 2,734
From: Virginia
I looked up the VSS in my fuel injection book. The book says it produces a ac sinewave. It says lift the drivewheels off the ground, put the tranny in drive and let it idle, and the VSS should produce at least .5 volt AC.
I looked up the code, and a bad vss will give a code 29, usually in the KOEO memory codes. He said this code is set when a vss signal is not received, and the other inputs to the ECA tell it the vehicle is moving. He doesn't say what these other inputs are, but I would guess it may have something to do with being at a certain rpm and in a certain gear. I am thinking it's impossible to get the engine to a certain rpm while it's in some of the gears, without stalling the engine.
Which brings up something else. These computers used the signal from the diesel tach for engine rpm. How have you duplicated this? The tach signal from the gas engine will be a lot different than the diesel tach signal running off the gear teeth on the injection pump.
I guess you know if you get desperate, they make a stand alone control unit for these trannies, but it's not very cheap.
I looked up the code, and a bad vss will give a code 29, usually in the KOEO memory codes. He said this code is set when a vss signal is not received, and the other inputs to the ECA tell it the vehicle is moving. He doesn't say what these other inputs are, but I would guess it may have something to do with being at a certain rpm and in a certain gear. I am thinking it's impossible to get the engine to a certain rpm while it's in some of the gears, without stalling the engine.
Which brings up something else. These computers used the signal from the diesel tach for engine rpm. How have you duplicated this? The tach signal from the gas engine will be a lot different than the diesel tach signal running off the gear teeth on the injection pump.
I guess you know if you get desperate, they make a stand alone control unit for these trannies, but it's not very cheap.
Thread Starter
|
Postmaster
Joined: Aug 2001
Posts: 4,270
Likes: 5
From: Delaware
I had the vehicle's back wheels off the ground and let it idle in drive. I didn't see anything that looked like a 0.5V Sine Wave.
I have a Microcontroller chip that I have programmed to simulate the Diesel Tach signal. It converts the gas engine tach signal to the diesel tach signal. Can you give me a description of that signal? Is it similar to the VSS. a 0.5 Volt Sine Wave?
There is a Baumann Transmission Control Unit on Ebay now, but his cable is for a 4R70W, and he wants too much for it.
I have a Microcontroller chip that I have programmed to simulate the Diesel Tach signal. It converts the gas engine tach signal to the diesel tach signal. Can you give me a description of that signal? Is it similar to the VSS. a 0.5 Volt Sine Wave?
There is a Baumann Transmission Control Unit on Ebay now, but his cable is for a 4R70W, and he wants too much for it.
Thread Starter
|
Postmaster
Joined: Aug 2001
Posts: 4,270
Likes: 5
From: Delaware
I never tested the ECU with the VSS unplugged. I removed the VSS and found that the speedometer gear turned free on the sensor. Somehow I got the wrong sensor. The center pin didn't protrude into the small hole in the gear. Everything looked OK, but when the gear turned it didn't turn the VSS or the cable. Since I don't have a cable hooked up, I never knew that it wasn't working.
Now it shifts into 3rd. I still have to implement the Overdrive Control Switch. I may just hard wire it 'On'. I don't anticipate needing to lock it out.
I also have to reprogram my tach-to-RPM conversion. The diesel ECU shifts to quickly. I can reduce the RPM frequency and allow the motor to rev higher between shifts.
Franklin, if you can find a description of the Fuel Pump RPM signals, similar to the VSS description, that would be helpful. I want to verify that my RPM signal is correct.
Now it shifts into 3rd. I still have to implement the Overdrive Control Switch. I may just hard wire it 'On'. I don't anticipate needing to lock it out.
I also have to reprogram my tach-to-RPM conversion. The diesel ECU shifts to quickly. I can reduce the RPM frequency and allow the motor to rev higher between shifts.
Franklin, if you can find a description of the Fuel Pump RPM signals, similar to the VSS description, that would be helpful. I want to verify that my RPM signal is correct.
Moderator
Joined: Jan 2001
Posts: 56,977
Likes: 2,734
From: Virginia
I looked up the diesel tranny wiring using what can be a unreliable source sometimes, and it shows the engine rpm signal going to pin 44.
So I look this pin up in my fuel injection book, and only two vehicles listed even use this terminal, and it's for some sort of "data communications link +". So I don't have anything to compare it to. I would think a 5v square wave would be a safe bet wouldn't it? And you will just have to play with the frequency versus rpm. I don't know how many teeth per revolution the diesel has. These old diesels are all mechanical, and those guys don't get into electronics very much.
So I look this pin up in my fuel injection book, and only two vehicles listed even use this terminal, and it's for some sort of "data communications link +". So I don't have anything to compare it to. I would think a 5v square wave would be a safe bet wouldn't it? And you will just have to play with the frequency versus rpm. I don't know how many teeth per revolution the diesel has. These old diesels are all mechanical, and those guys don't get into electronics very much.
Thread Starter
|
Postmaster
Joined: Aug 2001
Posts: 4,270
Likes: 5
From: Delaware
I looked up the diesel tranny wiring using what can be a unreliable source sometimes, and it shows the engine rpm signal going to pin 44.
So I look this pin up in my fuel injection book, and only two vehicles listed even use this terminal, and it's for some sort of "data communications link +". So I don't have anything to compare it to. I would think a 5v square wave would be a safe bet wouldn't it? And you will just have to play with the frequency versus rpm. I don't know how many teeth per revolution the diesel has. These old diesels are all mechanical, and those guys don't get into electronics very much.
So I look this pin up in my fuel injection book, and only two vehicles listed even use this terminal, and it's for some sort of "data communications link +". So I don't have anything to compare it to. I would think a 5v square wave would be a safe bet wouldn't it? And you will just have to play with the frequency versus rpm. I don't know how many teeth per revolution the diesel has. These old diesels are all mechanical, and those guys don't get into electronics very much.
The normal conversion ratio is 8/105. If I want the trans to shift at higher RPM, I can use X/105, where X is larger than 8.
I am driving pin 44 with a 5V square wave.
I have tied pin 41 (OCS) to VPWR(+12V). It should be going into OD, but I am not sure. I am going to hook up a tach and switch it between the Coil(-) and Tach(Pin 36). I should be able to see if my RPM signal conversion is working. Also, as I drive it, the tach will show the gear shifts.
While I'm here, I have a question about the Neutral-Safety switch. My old trans had a Neutral-Safety switch. The E4OD has the MLPS. How can I disable the starter in gear without a Neutral-Safety switch. Currently the Neutral-Safey connections are jumpered to allow the starter to operate.
Moderator
Joined: Jan 2001
Posts: 56,977
Likes: 2,734
From: Virginia
While I'm here, I have a question about the Neutral-Safety switch. My old trans had a Neutral-Safety switch. The E4OD has the MLPS. How can I disable the starter in gear without a Neutral-Safety switch. Currently the Neutral-Safey connections are jumpered to allow the starter to operate.
http://www.becontrols.com/tech/bectcsinstall.pdf
The Transmission Range Sensor or TRS (also known as Manual Lever Position Sensor or MLPS) is mounted
on the transmission shift linkage on the driver’s side of the transmission. It serves three different functions by
informing the TCS of which position the shifter is in (P, R, N, D, etc.), and also serving as the Neutral Safety
Switch (allowing engine cranking in only Park and Neutral) and the Backup Lamp Switch. The Neutral Safety
Switch can usually be accommodated by connecting to the original wiring, color-for-color, with a few
exceptions. Earlier vehicles use the same color wire going into and out of the switch (red with a blue stripe)
while the AOD-E harnesses will have a white wire with a pink stripe coming into the TRS from the “Start”
terminal of the ignition switch. On an earlier vehicle, simply match the white/pink wire with the vehicle’s
red/blue wire that feeds from the ignition switch. Backup lamps can be connected in a similar fashion, where
the feed wire from the TRS to the lamps is black with a pink stripe and will almost always match color-forcolor.
The fuse panel feed to the TRS for the backup lamps will probably be purple with an orange stripe
(although a Mark VIII harness will use white with light blue for this purpose) and will match many later
vehicles, color-for-color. Other vehicles may require investigation to determine which wire is the “hot-in-run”
feed for the backup lamps, before the connection can be made. Be extremely careful as the purple/orange color
code is also used at the bulkhead connector for shift solenoid #2 and interchanging these two wires will result in
improper gear selection, in addition to inoperative backup lamps.
Thread Starter
|
Postmaster
Joined: Aug 2001
Posts: 4,270
Likes: 5
From: Delaware
I am familiar with the Baumann TCS. You have to add $150.00 to the $400.00 price for the cable, or you can buy the Baumann Connectors for $50.00 and make your own cable. If this was a high-dollar truck, I would probably opt for the $450.00 option. I was able to get a Diesel EEC-IV and cable for much less. Working out the details has been a part time project for me.
I printed out the E4OD wiring diagram for the Baumann TCS. It does show the Neutral-Safety switch as well as the Backup Lamp switches. That information is not on the wiring diagram for the EEC-IV trans control unit. I should be able to get it wired now.
Thanks much!
I printed out the E4OD wiring diagram for the Baumann TCS. It does show the Neutral-Safety switch as well as the Backup Lamp switches. That information is not on the wiring diagram for the EEC-IV trans control unit. I should be able to get it wired now.
Thanks much!