2001 dodge cummins random downshifting - Dodge Cummins Diesel Forum
98.5-02 Powertrain Discussion of components that are directly involved in the power production and all that is needed to get and keep the truck moving . Engine , Transmission Ect..NO ADVERTISING .

 
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post #1 of 11 (permalink) Old 06-05-2019, 12:09 PM Thread Starter
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2001 dodge cummins random downshifting

Hey guys, I need some help. So I just recently noticed my transmission starts to downshift at around 40-50 mph at random times. Sucks, because on freeway it will basically get up to 55-60 then just fall flat on its face. I have already had the gov pressure solenoid and transducer replace a month ago. Was good for a while and now this problem occurred. I also noticed that my fuel pressure has dropped a little. Normally at idle I was at 18-20 psi and 14-16 psi wot. Now my fuel pressure is at 16psi at idle 12psi wot. I don稚 know if these problems are related, but I really want to hear what you guys have to say about this. Thanks for all the help in advance

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post #2 of 11 (permalink) Old 06-05-2019, 08:12 PM
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Alternator ac voltage check,

Maybe it's time to change the fuel filter.

'01.5 QC, SB, 6spd 4x4, Drag Comp, 4" exh. Jammer 100's, 62-65-.70A/R WG, adj.boost elbow Big Line, fuel press.pyro & boost gauges fuel cooler BHAF, Black Holley lift pump-12psi WOT Ceramic/Kevlar SD clutch, studs Take time to turn-so you don't burn
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post #3 of 11 (permalink) Old 06-06-2019, 02:36 AM Thread Starter
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Little update, after driving the truck home from work today my fuel pressure was fluctuating a lot. A few times my fuel pressure got to near zero, but didn稚 die out. I changed my fuel filter but when I went to bleed air out the system, upon bumping the starter the lift pump would not turn on. I couldn稚 hear the pump running after I bumped the starter. I tried a few times with no luck. I checked for power at the lift pump connector, there was power. Came to the conclusion, my lift pump was bad. I知 waiting for the replacement to come in the mail. That being said, I知 thinking the fuel issue may have been a separate problem lol. Thanks for ur advice on the alternator, I will definitely look into it and reply back with my findings.
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post #4 of 11 (permalink) Old 06-06-2019, 08:52 PM
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Good work, we'll await your findings.

'01.5 QC, SB, 6spd 4x4, Drag Comp, 4" exh. Jammer 100's, 62-65-.70A/R WG, adj.boost elbow Big Line, fuel press.pyro & boost gauges fuel cooler BHAF, Black Holley lift pump-12psi WOT Ceramic/Kevlar SD clutch, studs Take time to turn-so you don't burn
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post #5 of 11 (permalink) Old 06-09-2019, 09:08 PM Thread Starter
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Ok so I got the lift pump issue fixed. I知 doing the alternator ac noise check. What is the spec. Or range of the allowable AC voltage? I知 getting
(.048 - .052 VAC) is this an acceptable reading, or is my alternator done for?
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post #6 of 11 (permalink) Old 06-10-2019, 06:53 AM
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.030 or less if i recall...mopar1973man sells diode packs...

i have one with a 90 stud, but need the straight stud....just saw that he has both now.

02 Sport / 47re / 4" MBRP TBE / DAP 75hp sticks/ HX35W / GDP FUEL BOSS / DDRP02 / 3rd gen brakes / 4th gen steering / 2" Thuren / MC ARMS / 5100's /285/75/17
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post #7 of 11 (permalink) Old 06-11-2019, 10:49 AM Thread Starter
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Is it better to replace the diode pack or just replace the whole alternator?
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post #8 of 11 (permalink) Old 06-12-2019, 02:32 AM
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The diodes alone may work but ALWAYS retest before or after installation of them or a new alternator. Replacements must be tested out of the box as many are too high AC from the factory. Last time I went through 6 Napa and Nippon without finding a good one and ended up with a Bosch with.023v ac as best I could find. Nations and other aftermarket can be good. Forget all other so called fixes. Do make sure all battery and other connections are perfectly clean metal to metal tight connection.

99 2500, Quad cab, 4x4 47RE, BD pressure lock on it, small BD 90/140 chip on the VP 44 connection plug, 17" 3rd gen wheels. 3.55 diffs. Ruenell front bumper and warn winch, Rancho adj shocks. 663k miles.
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post #9 of 11 (permalink) Old 06-13-2019, 04:38 AM Thread Starter
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Alright, thanks for the help guys. I値l probably end up switching the whole alternator. Hopefully this eliminates my downshifting problems. I値l update you guys as soon as I find the time to replace my alternator
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post #10 of 11 (permalink) Old 06-13-2019, 06:54 AM
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i have about 80 bucks in rebuild parts.

mainly just because it is easy to do, and i feel better having done it my self.

i will need to test it once i do it, but i like knowing what/how i was done. very rarely do any of my vehicles have work performed by others.

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post #11 of 11 (permalink) Old 06-14-2019, 02:36 AM
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Be sure to test for AC upon installation and clean all terminals well too. Must use machine or good voltmeter with a just 2v scale, not 20 or 200v scale.

99 2500, Quad cab, 4x4 47RE, BD pressure lock on it, small BD 90/140 chip on the VP 44 connection plug, 17" 3rd gen wheels. 3.55 diffs. Ruenell front bumper and warn winch, Rancho adj shocks. 663k miles.
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