I have the Timbo APPS, fixed the previous Lock/Unlock issue a couple of weeks ago. Last weekend I hitched up or 5th wheel for a 3 hour trip. With the 5th wheel in tow, the dreaded Unlock/lock cycling came back, especially later on in the trip when the truck was good and heat soaked, or so it seemed. I have driven it to work (30 minutes each way) this week after disconnecting the 5th wheel, and the issue is again gone. I have previously checked for alternator noise, which was negligible. Is it possible that the charge circuit to the 5th wheel is inducing this problem, or possibly the extra heat in the transmission when towing? Any thoughts would help.

What is your AC noise reading? Have you done the W-T mod? 

13 minutes ago, Threadzy said:

What is your AC noise reading? Have you done the W-T mod? 

X2.

 

I have not done the W-T mod, I will double check the AC noise tonight. I do remember it being very close to what Morparman had in his AC Voltage how to video.

The W-T mod is a must on these trucks. 

I'll check the AC noise with and without the camper connected, and report back. I may try to do the W-T mod this weekend.

@Threadzy @JAG1 AC voltage measured 34-36 milivolts (.034-.036 volts) without the 5th wheel connected, measured 40-50 milivolts (.04-.05 volts) with it connected.

That .05 is at the high  limit. Do the W-T ground mod then retest. I wouldn’t be surprised if it fixed your lockup issue. 

It could be that A/C ripple becomes elevated when charging the Fifth wheel batteries and truck batteries same time. If you do the W-T wiring changes because the factory set up is wrong in the first place, you may see some good results

 

Place a load on the truck batteries and fifth wheel batteries and then have the RV hooked up. Start the engine and see what the A/C volts is showing 

 

How old are any of the 4 batteries?

Edited August 12, 20204 yr by JAG1

@JAG1Following the instructions in MoparMan's video, I turned off all accessories when checking the AC voltage. But you make an important point, what is it doing when the alternator is under load. I know I was also set to Max AC, blower on full blast, as my AC is a bit week and it was a sunny day in the 90's. The 5th wheel battery is brand new a month ago, the pickup batteries are pretty much at the end of their expected life cycle. I'm really concerned about this shortening the life of my transmission, I have another camping trip planned in two weeks. The truck is fine running around empty, no converter cycling at all. I think my plan of action will be to get the W-T ground mod done, then add a manual converter  lockup circuit that I've seen here. The manual lockup circuit should prevent the cycling, If I'm understanding that setup correctly?

Would the batteries in the pickup being weak possible cause this? I have a OBDlink, shows consistent 14volts

Edited August 12, 20204 yr by jltait

I was thinking the possibility of a couple old batteries in the fifth wheel. If one has an internal short would cause the alternator to be working hard, at possible full tilt, thereby raising the A/C ripple to run up an elevated amount. When it's hooked up, are there any 12 volt loads going on inside the RV?.

 

The single biggest offender to the electrical system is the B+ charge wire bundled up along side those grounds because AC voltages like to jump around outside the insulation. Then the 4 sensor grounds bundled together in not solder mind you, but some sort of melted plastic coating . Then you have the budget minded way the PCM grounding is done around and to the passenger battery. W-T explains it well why that is wrong.

 

I'm also wondering about the transmission TV cable adjustment. Just mentioning as a possibility even though the W-T rewire work will be a great benefit.

 

I would replace the truck batteries before you get a shorted cell and your poor alternator gets worked to death trying to keep up. Mine got so hot I couldn't go near it, it was smokin'. I had to replace it. New batteries solved my problem

Edited August 13, 20204 yr by JAG1

@JAG1 @ThreadzyAfter work today, I threw the meter on it again with the AC/blower on full blast. .06 v, so I'm in agreement that the AC noise is the problem. I am going to disconnect the current B+ cable to the electrical center and temporarily connect a new B+ connection to the passenger battery, then see what I get. I have a busy week, so I don't think I will be able to do the full blown W-T ground mod prior to next weekend's camping trip. I am hoping that moving the B+ will suffice for now. I installed a fuel pressure gauge earlier this week and noticed I do fall below the 10 psi threshold under hard acceleration, so I urgently need to get a Raptor on it this coming week too.

I did check the TV cable adjustment, seems about perfect. No slack or preload, moves the lever on the transmission immediately with throttle movement.

Thanks for the help

 

I hope you catch what's doing it. This site has helped a great many of us 

I'm currently like 9 to 11 mV AC last time I check after doing the W-T ground wire mod. Big difference to the 55mV AC I was before the W-T ground wire mod. My whole process is the simplified version.