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Roy
Roy, import/domestic specialest
Category: Transmissions
Satisfied Customers: 6175
Experience:  ASE master tech for 40 years
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I am fluctuating voltage and pressure for my transmission

Customer Question

i am fluctuating voltage and pressure for my transmission and cause me to burn out all forward gears
JA: When was your transmission fluid last checked?
Customer: its a fresh rebuild brought back and forth to tranny shop 3 times with 2nd rebuild now and when he put his scanner on was able to see intermittently voltage fluctuating when the pressure dropped
JA: What is the model/year of your Ford?
Customer: 1999 f350 EOS4x4 dually 7.3l
JA: Are you fixing your F350 yourself? What have you tried so far?
Customer: my tranny guy is out of options its costing him too much time and money so now i have to its either my wiring harness or my pcm
JA: Anything else you want the mechanic to know before I connect you?
Customer: yes my 4x4 does not work everything is replaced but no 4x4 light comes on when i start my truck.. is that with my computer also and/or could be the same problem with my transmission
Submitted: 2 months ago.
Category: Transmissions
Expert:  Roy replied 2 months ago.

hello, my name is ***** ***** I will be glad to assist you. please allow me a couple of minutes to gather some basic info.

Roy

Expert:  Roy replied 2 months ago.

are there any codes set in the trans??

what model trans???

Roy

Customer: replied 2 months ago.
it is not throwing any codes and is the 4r100 transmission it seems to only act up when the truck get warmed up
Expert:  Roy replied 2 months ago.

ok, with no codes it is not electronic controls. it would code if it was. it is a mechanical issue.

what does it do when it acts up???

Customer: replied 2 months ago.
its fluctuating voltage and transmission pressure everything is new in transmission its either the wiring harness or computer
Customer: replied 2 months ago.
im not driving it right now so i don't burn the tranny up for a 3rd time
Expert:  Roy replied 2 months ago.

what does it do when it acts up????

Customer: replied 2 months ago.
i was running a tsp performance chip and when it acted up it would take an extra long time to shift gears we took the chip off and its still acting up pressure and voltage wise but not noticeable when I'm driving because the added power isn't there without he chip
Customer: replied 2 months ago.
ts6*
Expert:  Roy replied 2 months ago.

ok what is the main line pressure???

I still do not think you have a harness issue. if you did there would be open circuit or short circuit codes set for components. I still think it is mechanical.

Roy

Customer: replied 2 months ago.
i don't remember what he said but I'm pretty sure it dropping to 100 but the voyage going to it goes up and down from 9.02- 11.4 v
Customer: replied 2 months ago.
i suppose ably went to the best tranny guy around even the other shops i called said they can't believe I'm having a problem
Customer: replied 2 months ago.
pressure ranging from 100-300? possibly
Expert:  Roy replied 2 months ago.

ok, what voltage is he checking???

300 in reverse is good. lower for drive ranges

Roy

Customer: replied 2 months ago.
Shift solenoid? I'm really not too sure I wouldn't be able to get an answer til tomorrow
Customer: replied 2 months ago.
It might be the range selector he had the volt meter on but I'm not sure
Expert:  Roy replied 2 months ago.

once again, if they were an issue there would be a code for voltage.

anyway, I was looking at flow diagrams and it looks like a valve body issue. nothing electronic just possible valves.

Roy

Customer: replied 2 months ago.
Again it was all replaced and upgraded not a mechanical issue when I have an intermittent voltage issue
Customer: replied 2 months ago.
I made sure internals and valves are all good was checked again after it was caught on the gauge
Expert:  Roy replied 2 months ago.

ok, you are not getting what I am saying. just because it was re done does not mean it is correct. there still could be an issue. you are stuck on an electrical issue which it is not.

I will opt out and see if anybody else can help you with this. we are not connecting.

have a great day

Roy

Customer: replied 2 months ago.
Thanks for your time I appreciate it