Can’t stop the ac noise

[skyhigh4by]

W-T ground mod done, replaced alternator diode pack, and cleaned up and coated all grounds I could find with dielectric grease. 

 

Im still getting 0.033v at idle and I’m still having a lockup issue. My tc tries to lock early(40mph)under light throttle and then instantly unlocks until I gain a bit more speed and then will lock up again. 

[Mopar1973Man]

Unhook your alternator and test again. Might have replaced the diodes but the brushes, slip rings, etc can still cause issues.

 

Then the output speed sensor on the transmission could cause shift issues too.

 

[skyhigh4by]

Ok thanks. How do I go about testing it unhooked? Suppose it would need to be on an alternator test bench? 

 

Does the speedo get its signal from the same output speed sensor because I haven’t noticed any issues with it? 

 

What about the apps could it be a culprit too? 

[Mopar1973Man]

31 minutes ago, skyhigh4by said:

How do I go about testing it unhooked?

 

Check the voltage at the battery. If it dropped the alternator still the cause. 

32 minutes ago, skyhigh4by said:

Suppose it would need to be on an alternator test bench?

 

That is a good second test too.

33 minutes ago, skyhigh4by said:

Does the speedo get its signal from the same output speed sensor because I haven’t noticed any issues with it?

 

No. The speed sensor is only for the PCM for shift data.

[skyhigh4by]

50 minutes ago, Mopar1973Man said:

 

Check the voltage at the battery. If it dropped the alternator still the cause. 

 

 

Okay so instead of grounding at the battery and testing the hot post on the alternator you mean just check for ac voltage right on the batteries themselves? 

[Mopar1973Man]

I'm just trying to find your source of the noise. If the alternator is removed then the noise should drop to ZERO or nearly. If so that just proves the alternator is still having issues. If you measure at the batteries and still have noise now we have to start digging to the source of the noise.

 

Bench testing the alternator is another good way to verify too. Just make sure they can measure AC ripple voltage.

[Dieselfuture]

I think best way to do it would be unplug the connector in alternator, field lead and undo the charge wire from alternator not the PDC, if you unplug the fuse in PDC ac noise will still be going through the charge wire next to other wires 

[skyhigh4by]

4 minutes ago, Dieselfuture said:

I think best way to do it would be unplug the connector in alternator, field lead and undo the charge wire from alternator not the PDC, if you unplug the fuse in PDC ac noise will still be going through the charge wire next to other wires 

 But with the w-t mod done the alt charge wire goes straight to passenger side battery? 

 

My alt doesn’t have the plug in type field wires. It has the block that the charge, ground, and field wires all go through so the field wires are on 2 little studs held on with nuts. I cut the charge and ground off that block thing. 

[Dieselfuture]

10 minutes ago, skyhigh4by said:

 But with the w-t mod done the alt charge wire goes straight to passenger side battery? 

 

My alt doesn’t have the plug in type field wires. It has the block that the charge, ground, and field wires all go through so the field wires are on 2 little studs held on with nuts. I cut the charge and ground off that block thing. 

You're right with WT mod, or was just speaking in general and missed that part. I guess if you unhook everything from the alternator and just leave the serpentine belt on, if you got a C noise at the battery, then it's not the alternator that's causing it. I think that's where Mike was heading with, then we'll have to figure it out what can possibly cause AC noise to backfeed. I'm thinking on plug fuses one at a time and see if it changes, obviously can't unplug the ones that make the truck run.

[skyhigh4by]

Okay so I’ve got some numbers. I’m not really sure what they are telling me so hopefully someone has some insight.

 

Alt connected to battery (w-t mod), truck at idle, no accessories running 

@battery 0.018acv

@alt B+ post 0.021acv

 

Alt disconnected from battery, still at same idle 

@battery 0.015acv

@alt B+ post 0.013acv

 

now I’m not a DVM expect but for some reason with it set to 2v AV and the leads not connected to anything it is reading 0.016acv. Is this normal? Should it not zero if there’s nothing connected to it? Almost seems like the voltage jumps around if I move the DVM or leads at all too? 

 

The numbers seem low(good) but I’m still having early TC lockup issues 

Edited May 10, 2019 by skyhigh4by

[Mopar1973Man]

The numbers look good and acceptable.

 

I would say the electrical system is good but you might talk to @Dynamic ask him about the lockup issue he might shed some light on it too.

[skyhigh4by]

Okay thanks

[skyhigh4by]

2 hours ago, Mopar1973Man said:

The numbers look good and acceptable.

 

I would say the electrical system is good but you might talk to @Dynamic ask him about the lockup issue he might shed some light on it too.

Could APPS have anything to do with it? I had truck on a scanner and at idle it’s reading .41v and WOT was 3.8v. 

 

Last time I checked it with DVM it seemed pretty linear through it’s range. 

[rambo]

I've been following this mod preparing to get started in a day or two. I'm no pro when it comes to electrical problems but any elect.generating source can add two these negative results. What about the tach generators in the front wheels used for ABS signals, don't they produce a A/C signal and the controller counts the freq. or rotation and if it stops it releases brake pressure for that wheel. Well the sensor feeds from wheel to controller pass very close to these mods your conducting. Has anyone considered this as a possible contributing factor and if it hasn't and  i'm the first how do i put my name on it?  Haha  trying to help and put it behind me.

[dripley]

4 hours ago, rambo said:

I've been following this mod preparing to get started in a day or two. I'm no pro when it comes to electrical problems but any elect.generating source can add two these negative results. What about the tach generators in the front wheels used for ABS signals, don't they produce a A/C signal and the controller counts the freq. or rotation and if it stops it releases brake pressure for that wheel. Well the sensor feeds from wheel to controller pass very close to these mods your conducting. Has anyone considered this as a possible contributing factor and if it hasn't and  i'm the first how do i put my name on it?  Haha  trying to help and put it behind me.

I am no expert either but I have done the mod and my wheel sensors wires are in the rear of the engine bay while the mod is in the front. As far as the tone wheels and sensors causing more ac voltage, that is well above my pay grade.

[Mopar1973Man]

I can't remember what dynamic said about the Torque converter lock up. I know it is controlled by the PCM and just grounding a wire for lock and unlocking of the TQ Conv. I'm not sure how the PCM makes the choice of locking or unlocking though. Speed sensor on the tail shaft? APPS signal? Engine RPM?  That why I suggested talking to him he would point you where you need to be. 

[skyhigh4by]

Okay. I already intended to get hold of dynamic in the next couple days. I’m hoping to get to his shop on an upcoming road trip. I am running his VB and got the rest of my trans parts from him. 

 

Being a Chevy guy I don’t know these dodge trannys well enough to tell if it’s actually functioning/shifting properly or not so hoping he can give a second opinion if I go see him. 

[Mopar1973Man]

Sad to say this is really old technology really. The A727 Torqueflite transmissions came out in 1962. Then it was upgraded to 4 speed in the mid 1990's which was an A618 or the 47RE. Basically, the same transmission from back then just changed out some parts add the 4th gear.