Another VPM issue

[WTW994]

So this forum seems to have the most resource for the dt444e VPM problems on the web.

I have a 1995 4700 rollback truck.

My warn engine light is on with the following flash codes
223
622
124
325
223
622

The light came on a few weeks after replacing my injectors. The truck starts and runs good but it is painfully slow. Especially up hill with a car on it. It does have some blow by it has 450k miles on it. But the worst part is I cant idle the motor up with the cruise control switch when Im using the PTO. Apparently it disables that feature when 622 code is on according to the service manual..

Ive replaced my icp sensor. I have 5 volt reference and ground.

I replaced both under hood ecm relays.

Now I had what I thought was a major break thru... I had an issue where the truck would not crank over. I replaced my crank relay under the passenger dash, my start relay under hood and I fixed a broken white ground wire in the harness under the motor on top of the front axle. I had the firewall connector off checking my voltages. After the truck was fixed the warn engine light stayed off for a day.

Two other issues I dont know if they could be related. Sometimes my gauge cluster stops working, sometimes it comes on and goes off while driving and the needles sweep back and forth like the whole cluster loses power and turns back on.

I have a NexIQ basic code reader and PID reader that wont connect since I started having these problems.

At this point is there any common places to look for a wire issue or do I need to buy the ford breakout box now? If my VPM is dead Im probably going to have to live with this problem. Maybe make a mechanical fix to idle it up with gas pedal. I just use the truck as a side hustle scrapping cars.

 

[WTW994]

So I removed my VPM and found a leaking capacitor on the circuit board. Going to attempt to solder a new one on. Truck runs without the VPM even plugged in.

 

[cadillackid]

So I removed my VPM and found a leaking capacitor on the circuit board. Going to attempt to solder a new one on. Truck runs without the VPM even plugged in.

the VPM isnt necessary for the truck to run but it runs at only default settings sotred in the ECM.. lowest Horsepower rating offered, least amount of features, etc..

 

[Omnibot2000]

So I removed my VPM and found a leaking capacitor on the circuit board. Going to attempt to solder a new one on. Truck runs without the VPM even plugged in.

Would be interesting to find out if it's the capacitors that are killing these things.

 

[WTW994]

Would be interesting to find out if it's the capacitors that are killing these things.

One of them looks like it could have damaged the board. Hoping i can just clean it up. Im waiting on the right tools to get here then I will try to fix it and provide an update.

 

[cadillackid]

One of them looks like it could have damaged the board. Hoping i can just clean it up. Im waiting on the right tools to get here then I will try to fix it and provide an update.

Wouldn’t surprise me , I’ve fixed a lot of things by replacing the caps .. no idea where in the line these are but if they are filter caps on the data link to the ECM they definitely would knock the VPM out of service on a short

 

[Omnibot2000]

Wouldn’t surprise me , I’ve fixed a lot of things by replacing the caps .. no idea where in the line these are but if they are filter caps on the data link to the ECM they definitely would knock the VPM out of service on a short

Same....the very first one I remember fixing was a TV that my parents was going to throw out. I even ran a trace on the circuit board. I was in my teens and it took me a week to get that TV working(all on luck as I had no clue but visual clues) but I had a TV in my bedroom after.

 

[cadillackid]

Same....the very first one I remember fixing was a TV that my parents was going to throw out. I even ran a trace on the circuit board. I was in my teens and it took me a week to get that TV working(all on luck as I had no clue but visual clues) but I had a TV in my bedroom after.

TVs and monitors are so often tossed out due to caps.. the heat dries out the caps and they either go open or they short and blow fuses.. result is the cnsumer tosses the device out..



recycling at its best is taking discarded items and repairingthem to work again!

 

[nikitis]

If you are gonna discard that VPM, send it to me, I'll attempt to repair it with soldering new traces on the board.

Let me know if you are interested in a Private Message.

 

[WTW994]

Soldered new capacitors to the board. Traces underneath look good. Still cant get my scan tool to communicate. Check engine still on. I got a break out box from ebay. Going to start messing with that see if it leads me to something I overlooked.

 

[DrewGerhan]

Did you ever get anywhere with this?

I think we are fighting similar battles. I have no ECM to VPM communication and I even bought a breakout box from eBay last week!

I ended up ordering what's supposed to be a new in box unprogrammed VPM. My buddy says he has NavKal software, so my plan was to try and have him program my new one this weekend.

 

[nikitis]

Navkal is way to go to program if he can do it for you.

There are 4 data lines total. 2x ACL Lines, and 2xDCL Lines. Two lines go from the VPM to ECM (DCL + and -) and two lines out to the 6 port J1708 plug (ACL + and -). Look up pin numbers in the EGES-125 Manual.

You need to unplug the VPM and ohms test from the VPM connector pin to the 6 port plug. Needs to be under 2 ohms I believe. If higher it could be a twisted pair resistance failure. If near 2 ohms it's likely okay, and you've ruled out wiring. This applies to all 4. The other pins from VPM connector to ECM pins. 2x wires. You'll need to look up which pins are on the ECM plug and test continuity and Ohms test as well.

If you find out after doing this test with a multimeter, that the wiring is good, then you need to test power and ground lines to the VPM. Without the VPM Plugged in, but with key on. If you have power and ground lines work, then you have a Dead VPM.

This is how I figured out I had a dead one as my wires were good, and ohms tested under 2 ohms.

 

[DrewGerhan]

Navkal is way to go to program if he can do it for you.

There are 4 data lines total. 2x ACL Lines, and 2xDCL Lines. Two lines go from the VPM to ECM (DCL + and -) and two lines out to the 6 port J1708 plug (ACL + and -). Look up pin numbers in the EGES-125 Manual.

You need to unplug the VPM and ohms test from the VPM connector pin to the 6 port plug. Needs to be under 2 ohms I believe. If higher it could be a twisted pair resistance failure. If near 2 ohms it's likely okay, and you've ruled out wiring. This applies to all 4. The other pins from VPM connector to ECM pins. 2x wires. You'll need to look up which pins are on the ECM plug and test continuity and Ohms test as well.

If you find out after doing this test with a multimeter, that the wiring is good, then you need to test power and ground lines to the VPM. Without the VPM Plugged in, but with key on. If you have power and ground lines work, then you have a Dead VPM.

This is how I figured out I had a dead one as my wires were good, and ohms tested under 2 ohms.

Did the wiring check and all is good resistance wise from J1708 to VPM connector and from VPM connector to ECM connector. Also power and ground are good at the VPM connector.

I really don't know how, but I think it's a dead VPM.

Thing that has me scratching my head though is the tach and speedo both work still... I through the VPM sent those signals from ECM to the cluster.

 

[nikitis]

Did the wiring check and all is good resistance wise from J1708 to VPM connector and from VPM connector to ECM connector. Also power and ground are good at the VPM connector.

I really don't know how, but I think it's a dead VPM.

Thing that has me scratching my head though is the tach and speedo both work still... I through the VPM sent those signals from ECM to the cluster.

It does not. My Speedo started working with a dead VPM after I replaced the Speedo sensor on the Transmission. So apparently it has a direct line to the ECM.

The gauge cluster most of them are set to all 0's (there's a dip switch panel behind it) and that is datalink mode which pulls the value from the ECM. The gauge cluster can be set to a dip switch to pull from other sources directly, but on buses it likely will be set to all 0's so it's coming from the ECM which is still working in your case.

You do have a dead VPM if the wires were ohms tested and continuity good. No doubt about it. I went through the same thing. We're told that VPM's are the least likely to die on us out of the 3 computers, and the IDM is the most common, yet since I've been here the last 3 years, I've seen more dead VPM's Those things are 30 years old so VPM's may have a shelf life around that long and we're starting to see more dead ones.

 

[DrewGerhan]

It does not. My Speedo started working with a dead VPM after I replaced the Speedo sensor on the Transmission. So apparently it has a direct line to the ECM.

The gauge cluster most of them are set to all 0's (there's a dip switch panel behind it) and that is datalink mode which pulls the value from the ECM. The gauge cluster can be set to a dip switch to pull from other sources directly, but on buses it likely will be set to all 0's so it's coming from the ECM which is still working in your case.

You do have a dead VPM if the wires were ohms tested and continuity good. No doubt about it. I went through the same thing. We're told that VPM's are the least likely to die on us out of the 3 computers, and the IDM is the most common, yet since I've been here the last 3 years, I've seen more dead VPM's Those things are 30 years old so VPM's may have a shelf life around that long and we're starting to see more dead ones.

Makes sense. Glad you had similar experience with the speedo, makes me feel better lol

I'll definitely report back after this weekend with how programming goes.

 

[nikitis]

Make sure your buddy knows that the ECM/IDM/VPM all need to be the latest version. If a VPM is too far off versions for example let's say the ECM is on Version 1.04, but the VPM is on 2.03, it will not talk to each other and appear as if it's dead. This is why you cannot just buy VPM's off of ebay without a NavKal programming capability. (You can but there's a 50/50 chance you may be in spec, but also not in spec so it's a risk) So if your buddy has issues, let him know he may have to update the VPM first, then update the ECM as the ECM and IDM programming physically goes through the VPM.

Those version numbers I just listed are 100% fictitious. Just providing a visual example.

The VPM can work with an ECM within a few minor versions off but not too many minor versions off. In many cases a Bus will never have had a chance to update the ECM and it could be on the first version still especially if it's a 1994-95 bus. A 1997 bus will likely have a newer less buggy ECM version out of the factory. Hardware they are the same, but firmware they are not. So let your buddy know they need to be compatible versions and we here at skoolie.net do not have a list of compatible firmwares or not. We just know that is the case.

So if he fails at programming it at first, it may have programmed the VPM but not the ECM, have him try to update the other two computers on navkal next and see if it all works next.

I believe the order it has to occur in is VPM first, then ECM, then IDM because the IDM is behind the ECM and isn't connected to the VPM directly.

 

[DrewGerhan]

Make sure your buddy knows that the ECM/IDM/VPM all need to be the latest version. If a VPM is too far off versions for example let's say the ECM is on Version 1.04, but the VPM is on 2.03, it will not talk to each other and appear as if it's dead. This is why you cannot just buy VPM's off of ebay without a NavKal programming capability. (You can but there's a 50/50 chance you may be in spec, but also not in spec so it's a risk) So if your buddy has issues, let him know he may have to update the VPM first, then update the ECM as the ECM and IDM programming physically goes through the VPM.

Those version numbers I just listed are 100% fictitious. Just providing a visual example.

The VPM can work with an ECM within a few minor versions off but not too many minor versions off. In many cases a Bus will never have had a chance to update the ECM and it could be on the first version still especially if it's a 1994-95 bus. A 1997 bus will likely have a newer less buggy ECM version out of the factory. Hardware they are the same, but firmware they are not. So let your buddy know they need to be compatible versions and we here at skoolie.net do not have a list of compatible firmwares or not. We just know that is the case.

So if he fails at programming it at first, it may have programmed the VPM but not the ECM, have him try to update the other two computers on navkal next and see if it all works next.

I believe the order it has to occur in is VPM first, then ECM, then IDM because the IDM is behind the ECM and isn't connected to the VPM directly.

Excellent information, thank you for this! I will share this with him before we get started.