Magnum and Wiring Swap

[tcanin00]

+1 on 75slant6's comment. Watch out for Cherokees too, I think a lot of them had security. Maybe you could google the PCM part number and get some answers on what it came out of.

If it turns out you do have a security PCM... well, before I make my next suggestion, let me say I hate Facebook groups for car advice. The nature of posts and comments for responses isn't great, I think a forum is much better. But there aren't a lot of guys on FABO that have done the EFI Magnum swap (certainly not as many as there are that could help you with just about any other Mopar related question). The Magnum EFI swap group on Facebook has a bunch of guys that know what they're talking about, so if you're not already a member you might want to join it. I searched through some old posts about the security issues and saw some responses, so you might be able to find the answer without posting a question of your own.

I'll look up the part number again and see what else comes up for it. A Google search is what identified the PDC and PCM. It was in a plastic tote that I bought with a manual transmission.
Yeah, I'm leary of Facebook groups. There are some knowledgeable guys in the groups. It's pretty easy to figure out who knows what they're talking about. I joined the Magnum EFI swap group and it seems decent. I'll post the PCM and part number and see what they say.

 

[DionR]

I ran across a tip years ago and saved it. The gist of the tip is that if you turn on the vehicle and then short the CCD or PCI bus wires and then turn it off while it is still shorted, the PCM will stop looking for the VTSS message and start. Assuming the vehicle doesn't have VTSS which would turn it right back on the next time you turn the power on.

If the PCM has never been in a vehicle with VTSS, it doesn't care if the signal is ever sent. Once the PCM is plugged into a vehicle with VTSS and the PCM sees the signal, it will always look for it even if it is then moved to a vehicle that doesn't have it. This is the source of the problem when someone plugs a borrowed known working PCM from a vehicle that didn't have VTSS into a vehicle that does have it, and then tried to put the PCM back into the original vehicle and it no longer starts.

I suspect this is a fail safe mode for the PCM. If the network is shorted before the PCM sees power, it waits for a good signal to do anything? But if the network is shorted while the PCM is powered, if figures something broke and goes into a fail safe mode and stays that way until it sees a good signal on the network?

The only real trick then is wiring in the PCI or CCD buss so you can short it. Even if just temporarily.

Note that I never tried it, so your mileage may vary. It was posted by an automotive technicians forum, so maybe it is legit?

Something else to note, I thought it was an issue with VTSS, not SKIM/SKREEM. Not really sure how they interact. If the SKIM/SKREEM module sends it's own code to the PCM, then it is an issue with those. But if it is an issue with the VTSS system and the PCM looking for a message from the CTM or some other module later on, then it is VTSS.

Either way, it is worth a try.

 

[DionR]

I was hoping to use the 1999 Dakota harness and PCM I already have. Is there a way to see if my PCM has a security feature?

I'll look up the part number again and see what else comes up for it. A Google search is what identified the PDC and PCM. It was in a plastic tote that I bought with a manual transmission.
Yeah, I'm leary of Facebook groups. There are some knowledgeable guys in the groups. It's pretty easy to figure out who knows what they're talking about. I joined the Magnum EFI swap group and it seems decent. I'll post the PCM and part number and see what they say.

My understand is that the PCM P/N will not tell you anything. The PCM's all come capable of a no-start security setup, but it isn't until they see a VTSS (or whatever) signal that it is activated.

The above is from a 2000 Dakota FSM.

In this case, the VTSS setup is enabled in the CTM.

 

[tcanin00]

I ran across a tip years ago and saved it. The gist of the tip is that if you turn on the vehicle and then short the CCD or PCI bus wires and then turn it off while it is still shorted, the PCM will stop looking for the VTSS message and start. Assuming the vehicle doesn't have VTSS which would turn it right back on the next time you turn the power on.

If the PCM has never been in a vehicle with VTSS, it doesn't care if the signal is ever sent. Once the PCM is plugged into a vehicle with VTSS and the PCM sees the signal, it will always look for it even if it is then moved to a vehicle that doesn't have it. This is the source of the problem when someone plugs a borrowed known working PCM from a vehicle that didn't have VTSS into a vehicle that does have it, and then tried to put the PCM back into the original vehicle and it no longer starts.

I suspect this is a fail safe mode for the PCM. If the network is shorted before the PCM sees power, it waits for a good signal to do anything? But if the network is shorted while the PCM is powered, if figures something broke and goes into a fail safe mode and stays that way until it sees a good signal on the network?

The only real trick then is wiring in the PCI or CCD buss so you can short it. Even if just temporarily.

Note that I never tried it, so your mileage may vary. It was posted by an automotive technicians forum, so maybe it is legit?

Something else to note, I thought it was an issue with VTSS, not SKIM/SKREEM. Not really sure how they interact. If the SKIM/SKREEM module sends it's own code to the PCM, then it is an issue with those. But if it is an issue with the VTSS system and the PCM looking for a message from the CTM or some other module later on, then it is VTSS.

Either way, it is worth a try.

Thank you so much for sharing this. I knew the 2nd Gen Dakota's had a much more complicated CAN/BUS network from reading performance/race builds using stand alone computers.
To be honest, I don't know if the PCM works or not. It seemed like a good deal when I was buying parts. I would hate to ruin a possibility good PCM shorting out the PCI/CCD circuit, or go through all of the work to wire it up and find out it won't work.

 

[DionR]

I would hate to ruin a possibility good PCM shorting out the PCI/CCD circuit

Shorting the network won't hurt the PCM. The network is a loop that goes high and low to created messages and shorting it just means communication on the network can't happen. It's not going to short the PCM and damage anything, it just means the PCM will see a communication issue and log the network as disabled.

 

[tcanin00]

Shorting the network won't hurt the PCM. The network is a loop that goes high and low to created messages and shorting it just means communication on the network can't happen. It's not going to short the PCM and damage anything, it just means the PCM will see a communication issue and log the network as disabled.

I could try that and see what happens. I would think if the circuit was open, it would acknowledge it as unable to communicate.

 

[DionR]

I could try that and see what happens. I would think if the circuit was open, it would acknowledge it as unable to communicate.

I think in order for it to work, it needs to see valid communication and then lose that communication. That's why power has to be on before shorting the network. If it is open, it just waits to see if the network is fixed and whatever it does to disable the no-start logic never happens.

Which brings up a point. You might need to have a CTM on the network before it will see a good network. On the later cars with CAN bus, there are 2 master nodes that form the start and end. If one is missing, the network doesn't work. Not all cars/networks are the same, but it sticks in my head that the CTM and PCM are all that is needed to make the CCD bus work. Not sure on the PCI bus networks though.

I had planned to install a CTM on my build and enable/disable VTSS using a fob. This would have given me a measure of security against hotwiring the car. An extension of the project would have been to wire the existing door switches into it and hooking it up to a horn and headlight relay so it could sound an alarm when a door was opened while the system was enabled. The last step would be to wire power door locks to the CTM as it is setup to unlock the doors through the same fob.

The nice thing about incorporating the CTM is then it shouldn't matter if the PCM is VTSS enabled or not.

 

[tcanin00]

That explanation makes sense.
Having an actual security system would be nice. I worry that someone is going to want my car more than I do and just take it. Harrisburg, PA has been more interested in murder than car theft, FWIW.
Would you be able to find a CTM out of another Dakota/Durango and program a fob to it, or does it have to be specific to the PCM?

 

[DionR]

That explanation makes sense.
Having an actual security system would be nice. I worry that someone is going to want my car more than I do and just take it. Harrisburg, PA has been more interested in murder than car theft, FWIW.
Would you be able to find a CTM out of another Dakota/Durango and program a fob to it, or does it have to be specific to the PCM?

I think any Dakota/Durango should work. Maybe even a van or truck, but not sure.

If you wanted to add the VTSS functionality, I think it has to be a highline or premium unit and should have had the VTSS enabled before hand. No idea on getting the fob programmed to it if you don't get one with it. Might have to take the rig into a dealer after you have it installed and running? Not sure.

 

[DionR]

That explanation makes sense.
Having an actual security system would be nice. I worry that someone is going to want my car more than I do and just take it. Harrisburg, PA has been more interested in murder than car theft, FWIW.
Would you be able to find a CTM out of another Dakota/Durango and program a fob to it, or does it have to be specific to the PCM?

Found this one - 56021223AI 1999 Dodge Dakota PL PW 4X4 AT Body Control Module BCM CTM | eBay

Listed for a '99 Dakota, but when I google the part number 56021223AI I found a listing for a '97- Ram as well.

 

[rbkt65]

autopar3000 is correct on the fb magnum swap forum. I belong to that forum and the guy that started it, Kerry Kinser, is a wealth of kmowledge as are a lot of the top contributors. KK makes easy to use wiring harnesses for you swap. I and a friend have his 1st design but later ones are really good and only use 3-4 wires to start a transplanted magnum.

 

[tcanin00]

Found this one - 56021223AI 1999 Dodge Dakota PL PW 4X4 AT Body Control Module BCM CTM | eBay

Listed for a '99 Dakota, but when I google the part number 56021223AI I found a listing for a '97- Ram as well.

Thanks again for the knowledge and research. I know a guy that parts out 1st and 2nd gen Dakotas so he might let me get a matching CTM, harness, and fob. A project for later on, for sure.

 

[tcanin00]

autopar3000 is correct on the fb magnum swap forum. I belong to that forum and the guy that started it, Kerry Kinser, is a wealth of kmowledge as are a lot of the top contributors. KK makes easy to use wiring harnesses for you swap. I and a friend have his 1st design but later ones are really good and only use 3-4 wires to start a transplanted magnum.

I joined that group and it seems decent. I haven't posted anything in it yet, but I've seen that Kerry is pretty active in it.
I might contact him to see what his opinion is on adding a CTM to my set up.

 

[DionR]

I joined that group and it seems decent. I haven't posted anything in it yet, but I've seen that Kerry is pretty active in it.
I might contact him to see what his opinion is on adding a CTM to my set up.

Make sure you post his response here, I haven’t ever really talked about the whole idea and am curious what others might think/know.

I am a member of the group, but would be easier to keep track of the info off FB.

 

[tcanin00]

I'll let you know what he says if and when I post in the group. I have never balanced time or money, so it's going to be a while before I get a CTM and the wiring.

 

[autopar3000]

Here's the easy button for a performance tune. Mopar Performance OBD1 PCM for the 5.9. Should work with the 5.2 just fine, maybe with a little extra fuel consumption.

Mopar 90s HIGH PERFORMANCE computer#5249546 - auto parts - by owner - vehicle automotive sale - craigslist

and

Mopar Performance P5249546


Of course, the risk is you have to hope these guys don't scam you, and when the PCM arrives at your door it actually works.

 

[autopar3000]

Question... you mentioned you're using the 904. Did you wire in a speed sensor?

 

[tcanin00]

Question... you mentioned you're using the 904. Did you wire in a speed sensor?

Thanks for the links to the PCM's, I'll check them out. Side note, I was scammed on a Mazda tech forum looking for a one year only PCM for a 1991 B2600i 4x4 that I had. After what seemed like a genuine conversation over the forum, I sent paid him for the computer to only hear excuses.
I haven't hooked up the speed sensor to the 904 yet. The Dakota used a gear driven VSS that fit in the place of a regular mechanical speedometer drive. I would like to keep my car's original speedometer, but I also need the VSS signal for the PCM and RWAL module. I have an idea of what I want to make for an adapter to drive both, but haven't got there yet. I am open to ideas and suggestions.

 

[tcanin00]

The new MAP sensor is waiting for me to finish up some other things I wanted to fix while waiting for parts. There were a couple of things that were wired wrong in the dash harness and I needed to make a bracket to hold the Dakota's multi function switch.

Since I wanted to keep the internet wiper function and module, I couldn't think of a way to make it work without the multi function switch. I gutted a spare Dart wiper switch and drilled the end of the stalk for the shaft.

I drilled and tapped the end of the plastic stalk for the threaded pin to go through the original shaft.
Then I put it together and test fit everything to a spare dash then I CAD, Cardboard Aided Drafted some cardboard to see if it would work.

My idea worked, but I wasn't happy with how the 1/16th aluminum bracket turned out. I couldn't find the 1/32nd stainless I thought I had, so I used some .028" stainless and hacked out another bracket.
Top view.

Rear and side views.

It will be a tight fit with A/C box and much thicker wiring harness, but I think it will work. I'll find out soon enough.

 

[DionR]

The new MAP sensor is waiting for me to finish up some other things I wanted to fix while waiting for parts. There were a couple of things that were wired wrong in the dash harness and I needed to make a bracket to hold the Dakota's multi function switch. View attachment 1716259304
Since I wanted to keep the internet wiper function and module, I couldn't think of a way to make it work without the multi function switch. I gutted a spare Dart wiper switch and drilled the end of the stalk for the shaft.
View attachment 1716259306
I drilled and tapped the end of the plastic stalk for the threaded pin to go through the original shaft.
Then I put it together and test fit everything to a spare dash then I CAD, Cardboard Aided Drafted some cardboard to see if it would work.
View attachment 1716259308
My idea worked, but I wasn't happy with how the 1/16th aluminum bracket turned out. I couldn't find the 1/32nd stainless I thought I had, so I used some .028" stainless and hacked out another bracket.
Top view.
View attachment 1716259309
Rear and side views.
View attachment 1716259310

View attachment 1716259312
It will be a tight fit with A/C box and much thicker wiring harness, but I think it will work. I'll find out soon enough.

Interesting!

 

[autopar3000]

The new MAP sensor is waiting for me to finish up some other things I wanted to fix while waiting for parts. There were a couple of things that were wired wrong in the dash harness and I needed to make a bracket to hold the Dakota's multi function switch. View attachment 1716259304
Since I wanted to keep the internet wiper function and module, I couldn't think of a way to make it work without the multi function switch. I gutted a spare Dart wiper switch and drilled the end of the stalk for the shaft.
View attachment 1716259306
I drilled and tapped the end of the plastic stalk for the threaded pin to go through the original shaft.
Then I put it together and test fit everything to a spare dash then I CAD, Cardboard Aided Drafted some cardboard to see if it would work.
View attachment 1716259308
My idea worked, but I wasn't happy with how the 1/16th aluminum bracket turned out. I couldn't find the 1/32nd stainless I thought I had, so I used some .028" stainless and hacked out another bracket.
Top view.
View attachment 1716259309
Rear and side views.
View attachment 1716259310

View attachment 1716259312
It will be a tight fit with A/C box and much thicker wiring harness, but I think it will work. I'll find out soon enough.

Hah hahaha.... that is pure awesomeness. And I thought I was fancy putting the Magnum cruise control setup on my car!

 

[DionR]

I haven't hooked up the speed sensor to the 904 yet. The Dakota used a gear driven VSS that fit in the place of a regular mechanical speedometer drive. I would like to keep my car's original speedometer, but I also need the VSS signal for the PCM and RWAL module. I have an idea of what I want to make for an adapter to drive both, but haven't got there yet. I am open to ideas and suggestions.

When I did my 5.9 SMPI swap on my Dakota, I was concerned that I would have to retrofit a '94/'95 Dakota IP into my '91. The '91 uses a cable driven speedo while the later IP uses a stepper motor speedo (or something similar). The big issue was that the '94 van I got my PCM out of for my swap used a 3 wire VSS and no cable pass through while my truck had a 2 wire VSS and a cable.

But then I tripped over this info. A 2 wire speed sensor will still work on a 3 wire system. The VSS pin on the PCM is powered and if you wire it to a ground through the 2 wire sensor, it will function just like it did using the hall effect 3 wire sensor. Only downside (I can see) is that the 2 wire sensor is probably mechanical in nature which means it will wear out while the hall effect sensor probably didn't have any moving parts and might last longer.

That's what I did on my swap. I just plugged in the '94 PCM to the '92 harness with the 2 wire VSS and sent it. Best I remember, the difference was that the '94 harness would have had the pin 7 8v supply feeding the 3 wire VSS while my '92 harness didn't. But the ground and signal pins for the 2 wire VSS were still connected. Worked fine, CC still works so it's getting the needed speed input.

Not sure how the RWAL works though. But removing the 8v supply wire from you VSS connection should make the 2 wire VSS with a cable work with the PCM.

 

[autopar3000]

Thanks for the links to the PCM's, I'll check them out. Side note, I was scammed on a Mazda tech forum looking for a one year only PCM for a 1991 B2600i 4x4 that I had. After what seemed like a genuine conversation over the forum, I sent paid him for the computer to only hear excuses.

I don't often buy from forums or online groups for that very reason. When I do take that risk I use Paypal goods and services and pay the extra fee. So far I have been lucky and haven't been burned trying to buy Mopar parts or parts for my 85 Supra. Yet.

I haven't hooked up the speed sensor to the 904 yet. The Dakota used a gear driven VSS that fit in the place of a regular mechanical speedometer drive. I would like to keep my car's original speedometer, but I also need the VSS signal for the PCM and RWAL module. I have an idea of what I want to make for an adapter to drive both, but haven't got there yet. I am open to ideas and suggestions.

I was asking because I didn't use a speed sensor when I was running a 904, and the engine use to backfire (afterfire?) through the exhaust on deceleration. Not like a modern performance tuned BMW, but it was bad enough that I didn't like it. Then I upgraded to a 46rh, but I wanted to keep my mechanical speedo so rather than figure out a solution I initially used pressure switches to control the OD and lockup.

Before long I found my answer: late 80s / early 90s mechanical speed sensor, like on a 91 Dakota (for example). As a bonus to having the PCM control OD and LU, and still having my mechanical speedo, I found as soon as I connected a speed sensor the afterfiring out the exhaust stopped happening on deceleration. Apparently the PCM will give the engine a bit of idle air on deceleration and that prevents the afterfiring. I have heard this problem doesn't exist with later OBD2 setups that aren't using a speed sensor, so maybe the engineers figured out a different way to prevent it from happening.

Here's the sensor I used:

More Information for STANDARD MOTOR PRODUCTS SC108

You can see one side screws into the speedo gear output on the transmission, there's a mechanical speedo output, and a 2 wire sensor connection. A few notes...

- I replaced my speedo cable with one from a 91 Dakota. It has a 5/8" nut as opposed to the 7/8" that would be used on the 904, and it has the push-on connector on the speedo side. At 80 inches it's a couple inches long even for my 46rh (but manageable), so it might be too much for a 904. I'm not sure if they make a shorter 68 inch cable with the 5/8" nut and push-on speedo end.

When I put in the 46rh I had one of these cables to extend my stock speedo cable to reach the 46rh speedo gear housing. I really wanted to find one with the 5/8" nut on the transmission end because that would have been perfect, but I couldn't find one anywhere.

I also looked into getting this guy's HM105T adapter, but he wanted some insane amount of money for what is essentially a nut with threads on the inside and outside, so I opted not to go with that. In hindsight, I should have just spent that money or had one machined locally. I didn't have fun replacing my speedo cable, and this would have made that unnecessary.

- You'll note that I mentioned it's a 2 wire mechanical sensor. One wire is the signal to the PCM, the other wire is a ground. The Magnum setup uses an electronic sensor, which has a 3 wire connector to the speed sensor: signal, ground, and power. With my setup I simply don't use the power wire and it works to control OD and lockup perfectly. I think the 2 wire connector is the same one from the OBD1 EVAP or EGR, because I had one in my pile of left over wiring that fit perfectly.

Also note that the later OBD2 setups don't use a speed sensor on the transmission, it's on the differential somewhere (I think - not on the trans, anyway). I think the last year for it on the trans is 1998, so if you do your OBD2 upgrade and use a later PCM and you need a speed sensor for one reason or another, you will have to consider this.

I think that covers everything, and should hopefully give you some options to consider.

 

[autopar3000]

Seems like me and DionR are speaking the same language here

 

[tcanin00]

Hah hahaha.... that is pure awesomeness. And I thought I was fancy putting the Magnum cruise control setup on my car!

Thanks! I wanted to keep as many of the Dakota's modern (in comparison) features as possible. Cruise control is on the list too, just have to figure out how to drive the VSS and the speedometer.
I would like to see how you made the cruise work, if you don't mind.