So I've come to the almighty moparman forums seeking help on an unusual issue I'm having. My truck is heavily modified by the previous owner and I'm constantly having to fix one thing or another and chase things.

So I have 2 issues now 1 of which I believe I know the issue but don't know a good fix.

First issue is I get trans limp mode and a P1689 with no buss on the CCD when turning on the HVAC blower at any speed. Once turned off it goes back to normal. I have taken the ground off for the HVAC controls and the no buss issue also happens without the blower motor running only in face vents or floor vents position.

Looking at wiring diagrams I can't tell where any of the HVAC would cross with CCD modules.

Second issue I'm having is TCC lockup. I have increased line pressures and a DTT box to decrease the voltage to 4.5v all the time. It engages sometimes but not others and the only way I can tell is just by RPM at 60mph. It's 1 tick below 2000rpm with 4.10 ratio rear. I believe maybe the DTT box is bad or the line pressures are too high? What is the TCC lock up algorithm? Sometimes if I left off the pedal and slowly accelerate it will be locked. It's easier to tell if it's locked when I'm towing which is what I use the truck for.

Thank you for any help! I'll provide any info y'all need and hopefully I can get this all figured out!

Edit* forgot to mention I have done the following things to try to fix both issues.

PCM grounded to pass side battery negative

W-T mod

New batteries and alternator

Disconnected a/c relay and compressor( didn't fix so I guess it's not in the a/c circuit)

Edited Friday at 05:25 PM5 days by ducktape11
Added info

UPDATE

Did the APPS reset and didn't change anything. It reads 0-100%. It is not very fluid though it jumps but like 7% at a time going up and down. Is is supposed to do that? Also is the INJ pump voltage supposed to be 12v or bat voltage?

Driving around I couldn't get the TCC lockup unless I left off the accelerator to the RPM where it should be with TC locked then push back into it. After that it stays locked at all speeds even if I have to slow down and speed up as long as I stay in 4th. If I slow down enough for 3rd then I have to do it all over again in 4th. This leads me to believe it's a line pressure issue of not being enough?? I have messed with the pressures before but until today I haven't actually tested what they are. Once my gauge setup gets here today I'll get the hard data and drop the pan.

Might actually do pressure gauge testing to see where your transmission pressures are at. All the pressure test ports and pressures are in the Dodge FSM.

On 4/18/2025 at 9:52 AM, ducktape11 said:

First issue is I get trans limp mode and a P1689 with no buss on the CCD when turning on the HVAC blower at any speed. Once turned off it goes back to normal. I have taken the ground off for the HVAC controls and the no buss issue also happens without the blower motor running only in face vents or floor vents position.

I suspect that you may have a poor body to frame ground, or poor body to battery ground. Since the blower motor switch grounding and the data link grounding are in the body ground circuit, a poor body to frame or body / frame to battery ground connection could influence the CCD circuit. Body ground # 200 (located on the driver side inside the cabin) and engine ground # 107 are part of the CCD circuit.

You could temporarily run a jumper cable from the body directly to the battery ground post and then operate the HVAC blower fan to see if the symptoms go away.

• John

You could temporarily run a jumper cable from the body directly to the battery ground post and then operate the HVAC blower fan to see if the symptoms go away.

That will work. Simpler yet a piece of 12 or 14 AWG cable between the driver side terminal and a fender bolt or body bolt of your choice.

Tested line pressure at the accumulator port and showed:

64psi at idle

85psi at 1800rpm

95psi at WOT

from what I can tell these are stock 47re numbers. I have a shift kit and aftermarket valve body at the minimum. Not sure on other internals. Shouldn't my pressures be 10-15psi higher?

When I turned the screw last time I fear I might have turned clockwise instead of counter clockwise and turned my pressures down. That could have been when the issues started but I'm not sure as I didn't notice the TCC issues until I started towing my 14k lb camper last year.

9 minutes ago, Mopar1973Man said:

That will work. Simpler yet a piece of 12 or 14 AWG cable between the driver side terminal and a fender bolt or body bolt of your choice.

Add another body/frame cable from battery?

Edited Monday at 08:16 PM2 days by ducktape11

Yeah, I would figure a bit more line pressure is in order. I would consider giving a transmission shop like DTT or similar a call and get good performance pressure specifications from them. Sadly, I'm a bit thin on automatic knowledge but yes, typically more line pressure is used in modified trucks. I'm trying to remember that something in the low 100 realm of pressure is typical. That's where the DTT box will control the max pressure signal back to the PCM. Just spitballing...

These are the line pressure values of my Dynamic built Stage 2 transmission. I hope this helps.

Line pressure test conducted with 300 psi gauge connected at rear servo test port (port #1) per FSM.

@ idle (800 rpm), transmission in drive truck stopped- 85 psi.

Light throttle:

2ed gear-105 psi.

3ed gear-110 psi.

4th gear-120 psi @ 2200rpm.

Wide open throttle:

1-2 shift...180 psi @ 2800 rpm.

2-3 shift...175 psi @ 3100 rpm.

3-4 shift...150 psi.

100% throttle 4th gear TCC locked @70 mph 160psi.

Edited Tuesday at 01:03 PM1 day by IBMobile

12 hours ago, IBMobile said:

These are the line pressure values of my Dynamic built Stage 2 transmission. I hope this helps.

Line pressure test conducted with 300 psi gauge connected at rear servo test port (port #1) per FSM.

@ idle (800 rpm), transmission in drive truck stopped- 85 psi.

Light throttle:

2ed gear-105 psi.

3ed gear-110 psi.

4th gear-120 psi @ 2200rpm.

Wide open throttle:

1-2 shift...180 psi @ 2800 rpm.

2-3 shift...175 psi @ 3100 rpm.

3-4 shift...150 psi.

100% throttle 4th gear TCC locked @70 mph 160psi.

I turned up the pressures to 75psi at idle and 110PSI WOT.

I still need to let off the pedal and ease it back to lock up the TC and then it holds fine. Also I have to drop the pan again and adjust the TV screw because it's downshifting is horrible. I need to turn clockwise correct??

Where should I go from here for the TCC lockup symptoms. I'm kind of lost at this point. I'll clean up the body and frame grounds as well.

Do NOT grind big patches of clean metal. Just remove a bolt or screw and leave paint intact. Other than that the grounds rust out rapidly and fail quicker. Make sure you metal is painted. Just the bolt or screw needs be clean and cut fresh threads maybe drill a new hole? DO NOT GRIND TO BARE METAL!

21 minutes ago, Mopar1973Man said:

Do NOT grind big patches of clean metal. Just remove a bolt or screw and leave paint intact. Other than that the grounds rust out rapidly and fail quicker. Make sure you metal is painted. Just the bolt or screw needs be clean and cut fresh threads maybe drill a new hole? DO NOT GRIND TO BARE METAL!

Where should I add a ground?

I disconnected the alternator and drove it with no changes. Let up on the pedal to around where it should be in lockup and push the pedal back and magic TCC lockup until I drop a gear......

Also I ran the multimeter onto all the grounds in the engine bay and they were all at battery voltage no drop.

Edited Tuesday at 11:39 PM1 day by ducktape11

With wide open throttle the up shifts should occur @2800-3000 rpm. The transmission cable at the throttle bell crank is where you can adjust that.

45 minutes ago, ducktape11 said:

I ran the multimeter onto all the grounds in the engine bay and they were all at battery voltage no drop.

Was this doing a voltage drop test?

19 minutes ago, IBMobile said:

With wide open throttle the up shifts should occur @2800-3000 rpm. The transmission cable at the throttle bell crank is where you can adjust that.

Was this doing a voltage drop test?

I'll try to adjust the cable tomorrow but my upshifts seem okay. It is having an issue downshifting from 3rd to 2nd now so I need to turn the TV screw in.

I was looking at bat voltage and testing at each ground.

I also did voltage drop tests on the cables wherever I could find cables and they were all 0.00v

1 hour ago, ducktape11 said:

I was looking at bat voltage and testing at each ground.

I also did voltage drop tests on the cables wherever I could find cables and they were all 0.00v

Are you doing your voltage drops correctly? Is the engine running with lots of electrical devices turned on to full power? If you are doing this test without the engine running and no electrical devices are operating, then the results of this test are meaningless.

A voltage drop in a normally operating electrical circuit will always register more that 0.00 volts. Typically, you would see up to .1 volt drop while a good circuit is operating.

Since you are having the strange issue of setting a P1689 with no buss on the CCD when you turn your HVAC blower on, this would be a good place to perform a voltage drop test. Start the engine and turn the blower fan to "high" speed. You will want to measure the voltage drop from ground connection # 201 (Instrument Panel Right Center Support) to the negative post of a battery. The blower must be operating on high speed. A .1 volt (or less) drop would be considered normal - a 1.5 volt drop would be a problem. If your meter reads 0.00 volts, then you have a poor connection with your meter.

• John

9 hours ago, Tractorman said:

Are you doing your voltage drops correctly? Is the engine running with lots of electrical devices turned on to full power? If you are doing this test without the engine running and no electrical devices are operating, then the results of this test are meaningless.

A voltage drop in a normally operating electrical circuit will always register more that 0.00 volts. Typically, you would see up to .1 volt drop while a good circuit is operating.

Since you are having the strange issue of setting a P1689 with no buss on the CCD when you turn your HVAC blower on, this would be a good place to perform a voltage drop test. Start the engine and turn the blower fan to "high" speed. You will want to measure the voltage drop from ground connection # 201 (Instrument Panel Right Center Support) to the negative post of a battery. The blower must be operating on high speed. A .1 volt (or less) drop would be considered normal - a 1.5 volt drop would be a problem. If your meter reads 0.00 volts, then you have a poor connection with your meter.

• John

Currently the blower ground is disconnected from that ground splice in the center dash. The CCD buss issue still occurs with face and floor vent settings without the blower running. Is there a master ground for the whole dash somewhere? I've tried moving the ground of the blower to different locations and still no luck. It does the CCD buss message and limp mode on any setting with blower running and without the blower connected it does just room air face or floor.

You didn't answer any of the questions regarding how you did your voltage drop test. A voltage drop test will give you conclusive information regarding whether or not the circuit you are testing is good or bad. It is one of the best electrical tests that one can do, but is also one of the least understood.

Reconnect the blower motor ground in the center dash. Connect your multi-meter to that ground and the battery post ground. Set the meter to DC volts on the 00.00 scale. Start the engine and turn the blower fan to high. Read and record the voltage drop. Any voltage above .1 volts during this test is considered to be excessive - the higher the number, the worse the condition . If this is the case, this means that the dash / body is not at full ground potential. This will affect the operation of any electrical devices that use the body as a ground.

I like doing voltage drop tests when I find it difficult to solve an electrical problem. Voltage drop tests don't lie, but you do have to be meticulous when you perform them. The best part of using this test is that you do not have to disturb any electrical connections in order to perform the test. Done properly, voltage drop tests save time and provide accurate conclusions.

Maybe you already know all of this, but I can't make that assumption.

I believe there are two body-to-battery grounds for the driver side battery. One is located on the body between the driver side battery negative post in the headlight area and I think the other is under the battery tray.

• John

Edited 9 hours ago9 hr by Tractorman

19 minutes ago, Tractorman said:

I believe there are two body-to-battery grounds for the driver side battery. One is located on the body between the driver side battery negative post in the headlight area and I think the other is under the battery tray.

I've seen posts over the years where people have found the ground points mentioned above to be corroded.