Where would I find a video or something to visually see what I should do, or like instructions or something

 

This has always been the weakness of this forum....there are very intelligent and experienced technicians on here that genuinely want to help,like yourself Mark,but there are those of us who do not possess your knowledge and have no idea what you're saying...and I'm sorry, but making us feel ignorant for it isn't fair either...again,my son and I just followed Mark's directions for changing the Mercon V fluid in my E4OD this past weekend and I greatly appreciate it, but please understand that sometimes we don't have a clue what you're trying to tell us to help....

 

You want a video of how to use a multimeter to test the wiring?

The title of this thread is “This is hypothetical, e4od troubles”. In the first post the OP states that “The shop replaced the TPS, and I hope that fixes it (knock on wood). Buttttt, If it doesn’t, what should we do next?”

The thread started yesterday and the light hasn’t come back on so is the truck repaired or is the problem still there? I think Mark asking if this is an actual problem is valid.

 

Again, you completely misunderstood my response...some of us can tear a motor down and rebuild it ourselves...my son and I have a 94 F150 XLT that was a 302 to 351 swap...then the fuel injection was swapped for a 4bbl intake and carb...we pulled the fuel pumps and took them apart and kept them for the sending units and put in an inline pump and actuator to still use both tanks....but I don't have a clue what or where a PCOM is...my truck has a MSD ignition, distributor, and coil....my point is that there is a huge difference between tech knowledge and mechanical skills....again,I greatly appreciate all the help and advice but some things all of us do not understand. My response was not to disrespect anyone, especially Mark,but again, we just don't understand

 

I asked if this was an actual problem because the title of the thread says that it is a hypothetical problem. If it is hypothetical by definition it is not real.

A PSOM (Programmable Speedometer/Odometer Module) is a printed circuit board bolted to the back of the instrument cluster. It takes in the vehicle speed signal from the VSS (Vehicle Speed Sensor) and turns it into a signal that the PCM (Powertrain Control Module) can use.

Most likely your entire problem is due to a problem in the wiring harness, most likely between the PCM and the VSS. You can disconnect the PCM and the VSS from the harness and check the wiring.

Here is how to check the wiring:

First NEVER put a probe in the end of the connector that makes the connection. This will open the pins and cause a new connection problem that you didn't have before you started. ALWAYS probe the back side of the connector where the wires enter. Your probe can touch the metal of the pins this way and not damage the connection.

Find the two wires on the PCM connector (you'll need a wiring diagram. I don't have one for your truck) and with the multimeter set on ohms, read the resistance from the PCM to the VSS connector for each of the two wires. Ideally, it should be 0 ohms, but it is never quite that low. I usually accept anything under 10 ohms. If you do get a good reading. tey jiggling the harness in several places. This may find an intermittent connection problem.

Next, with one probe on one of the circuits (either end) touch the other probe to a good ground, such as the battery negative post. This should show an open circuit. Next, touch the other probe to the battery positive post. This should also show an open circuit. If either shows anything besides an open circuit you have a short circuit.

 

When I don’t understand the terminology, I look it up. I did a search of “where is the PSOM located” and found pages of pictures. The PSOM is the part with the white “X”


Then I looked up its function and found pages of descriptions. Here is a partial description from one of the websites:



I get that you can’t know everything about every vehicle but sometimes you need to help yourself figure out what was said. I search through threads trying to find answers before I ask a question which is why I don’t start a thread very often. These trucks are 30 years old and more often than not my question has already been answered at least one other time. Most likely you could have found the PSOM answer in threads using the search function here.

 

I called it hypothetical only because this truck has a track record of continuously messing up no matter what advice we take on fixing it, I was hypothetically asking or maybe I should have said “In the case that”, if this doesn’t work where should the next step be taken.

And there was never a light on, Just an apparent and obvious problem, Plus a code. It hasn’t come back but like I said it just doesn’t happen all the time, and after we clear the codes it takes about 100 miles

My only question now is Where is this vss test connector Prototypemech is talking about?

 

The VSS is the Variable Speed Sensor...it's located on top of the differential at the rear end...it has a two wire clip (be careful it'll break easily) and is held inside the differential by i think a half-inch bolt...I had to change mine a while back but that's all I know...Mark Kovalsky really is the expert as are others but they seem to get irritated by us who don't understand the computer/sensor stuff...this is why my truck is a hybrid 4bbl with a MSD ignition control box....something I can work on

 

Mark are you talking about the connection to the variable speed sensor on the differential? Is that where you are saying test with the ohm meter? If it shows a short,then follow those wires back to the computer?

 

Yeah I know I’ve replaced it twice, I was talking about the test connector that mark and prototypemech was talking about. I would definitely like to get that reading

 

I messaged on the thread to ask Mark for sure what he's describing...I think he's talking about testing the wires that connect to the sensor...but...test from the back of the connector by putting the probe in the back of the connector...not the front...I wish I knew how to send a picture but I don't

 

There is a video on YouTube

 

Thank you ABR3, I’ll watch that, what did you look up, or do you have the link?

 

I’m not see anything about some test connector.

In post #15 Prototypemech said to disconnect the VSS at the sensor and check the resistance.

In post #20 Mark said to disconnect the wiring at the VSS and also at the PCM to test each wire. He also told you how to perform the test.

 

This is on post #2:

Has anyone put a Oscilloscope on the test connector for the VSS and see what its doing? The VSS test connector gives raw VSS signal. If that signal is good, next thing to do is to test the connector on the cruise control servo.

You can also read the full post for context, I know it seems odd