Batteries and Gear Hunting

[gnjsmall]

OK, this is one of those posts where you saw articles and posts about this in the past and you cannot find the thread where you originally read it.



A few years ago a read a thread about how the weakness of a battery or batteries could impact the transmission shifts. Around 90K I started having a lot of shifting issues with my 05' 4x4. I would punch it and it would drop out of OD and just spin like crazy. I also got a lot of gear hunting at light throttle take offs.



I had read the postings and thought, nah, my transmission is going. So I paid for the ATS built with the 5 Star Torque converter. Boy was I shocked when I picked it up and the gear hunting was still there.



A year and a half later my stock batteries finally gave out at 120K. One battery would not take enough charge to even test and the other one registered bad. I went for the Yellow Top Optimas in hopes that these batteries would last the next 200K.



So, I will get the inevitable "check Issue XX, page XX" we told you so posting on this, but if your transmission starts gear hunting, change the batteries first. They cost a lot less than a built transmission!!!



I am certainly not sad I got the transmission, now it is fairly bullet proof and will take all the lb-ft I will ever throw at it.



Thanks- GNJSMALL



2005 2500 4x4. Banks cool air with the scoop, ATS Arc Air, Banks turbo back exhaust, ATS transmission with 5 Star torque converter

 

[Prairie Dog]

I'm not sure how a battery could effect trans shifts since thats all mechanical and only the final shift into OD is electrically actuated.

 

[chipster]

I'm not sure how a battery could effect trans shifts since thats all mechanical and only the final shift into OD is electrically actuated.

the`05 transmissions are electric shifted. :-laf and all trans after `96 are electronic shifted. that`s why they are called 47re, 48re etc,etc.

 

[cerberusiam]

the`05 transmissions are electric shifted. :-laf and all trans after `96 are electronic shifted. that`s why they are called 47re, 48re etc,etc.

An 05 48RE are no more electronically shifted than the a 96 47RE. Its the same unit with some hard part upgrades. When they are electronically shifted they are the FE designation, 545RFE or 69RFE.

I'm not sure how a battery could effect trans shifts since thats all mechanical and only the final shift into OD is electrically actuated.

Governer pressure influences 1-2 and 2-3 shifts by playing against the TV pressure. The gov pressure on an RE transmissions is controlled by the TCM using the gov pressure transducer and solenoid. The gov pressure needs to start and end at a certian point and the pressure rise be smooth and comparable to wheel speed or you get flaky shifitng.



A bad battery will introduce voltage fluctuations and noise into the what the ECU is reading off the sensors and cause all manner of issues. It shows as the same problem as a bad ground. The CR's are just more susceptible to the [porblems because there is so much more electronics and the demand on the batteries is a lot higher.

 

[gnjsmall]

Thanks

I could not honestly remember why it would impact it either. Even it it is electric, wouldn't the voltage come indirectly from the alternator instead of the battery?



Any-who, I can assure anyone reading this that that truck runs 100% better than it did. So even if it is 2012 Mayan Voo-doo magic, I am very pleased and would recommend that anyone try replacing the batteries before getting a built transmission.



:-laf



- Gnjsmall

 

[cerberusiam]

I could not honestly remember why it would impact it either. Even it it is electric, wouldn't the voltage come indirectly from the alternator instead of the battery?

All electrical feeds are from the batteries. The state of the batteries is the only condition that effects the electrical systems.



Voltage draw is not the problem as most of the ECU sensors are 5 volt. Its the amount of draw in amps that will throw a dirty voltage signal into the system. The battery will maintian 12 vots but amp draw down due to a failing battery wil cause noise in the signal.

 

[gnjsmall]

Thanks cerberusiam. Your explanations are very clear and easy to understand. I think I can speak intelligently to this in the future. I appreciate you putting it in terms the 'lay person' can clearly understand. This was very helpful.

 

[BGlidewell]

It would not be an exaggeration or a bold assumption to say weak batteries are the source of millions of dollars in mis-spent repairs every year with diesels. Seen it time after time.