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4R100 1st-2nd shift problem.

46K views 28 replies 5 participants last post by  Koty 
#1 ·
Ok so I'm sure this has been covered quite a few times. I've searched this topic for a few nights while at work on this specific forum as well as a few other forums that's I've came across on google.

I have a 2001 Excursion. Build date is 8/00 so I'm guessing that I do not have the mechanical diode in my transmission? I could be wrong though. Anyways, I bought my 2001 Excursion at the beginning of April 2017. It's a 7.3 4x4 and has 138k on the odometer. It's completely stock and I bought it off the original owners who are an older couple so it was never abused. I bought it knowing it was having transmission problems. The previous owner claimed it had no power and they couldn't afford to fix it. While viewing the vehicle I noticed it had a fuel leak around the filter bowl so that was problem number 1. I also noticed the shift solenoid on the transmission was unplugged which was causing it to start in 4th gear, there's problem number 2. I trailered it home, got it off the trailer and replaced the fuel filter and gasket then shortly after that I plugged in the shift solenoid. No more fuel leak and also all 4 gears work. The problem that I encountered afterwards is that 1st gear will not shift into 2nd gear unless I rev to 2500+ RPMs then let off the throttle. The transmission fluid is at normal operating level, looks bright red but somewhat smells like an electrical burn. The odor isn't strong by any means but it's slightly noticeable. I did have 2 codes pop up whenever I brought it home as well as the OD light flashing. The codes that popped up were P0743 and P0755. I cleared the codes and have driven the excursion 50 miles without any lights popping back up. When I recently unplugged the female end of the solenoid plug I noticed that it has slight fluid build up on it. Is that normal? I'm thinking this has to be a wiring issues, something small that I cannot pin point on my own. I'm confused as to what it can be so I'm hoping someone here can point me in the correct direction. I plan on ordering a pigtail harness that will plug into the solenoid so I can test it without dropping the pan and removing the solenoid. Is there anything else that I should check? This has been bothering me for quite some time. I had originally planned on taking it to a transmission shop and have someone experienced take a look at it but if it's something simple then I'd like to fix it myself and save some money. I called one shop, told them my issue and they automatically told me I needed a rebuilt transmission ($2,950 w/o tax). Any help would be greatly appreciated. Thank you in advance.

My reverse gear also works great if it makes a difference.
 
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#2 ·
Congrats that is one nice rig and low miles!!

So since you plugged the trans solenoids back in and cleared the codes
Trans is still hanging in 1st, delayed shift into 2
and no more flashing light?
 
#4 ·
Does solenoid B control the 1-2 shift?
Sorry I am new to 4r100
your second code from memory was a solenoid B issue

The next step would be to OHM the solenoids from the wiring plug on the side of the trans
This will tell you if your shift and pressure control and converter control solenoids are within spec
 
#5 ·
To be honest with you I don't know what solenoid b controls. And yes, I had planned on testing the OMHs from the solenoid but I wanted to order an additional pig tail harness so I can test it without having to drop the pan. It looks too difficult to test it in place without a spare cut harness.
 
#6 ·
#7 ·
I have a 2001 Excursion. Build date is 8/00 so I'm guessing that I do not have the mechanical diode in my transmission?
Build dates for the mechanical diode was 7/00 to 2/01. Your truck left the factory with a mechanical diode transmission.

The problem that I encountered afterwards is that 1st gear will not shift into 2nd gear unless I rev to 2500+ RPMs then let off the throttle.
That's the classic symptom of a failed mechanical diode.

My reverse gear also works great if it makes a difference.
No, it doesn't. The mechanical diode doesn't affect reverse gear.
 
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#8 ·
Yes sir that's exactly what I had planned on ordering. I'll go ahead and order one tonight while I'm at work. Also, I have a friend with a brand new Ford solenoid pack that he's selling for $250. He bought it through Ford and ended up doing a ZF6 swap.
 
#10 ·
dang Ford WTF!!!! Diodes are for fuse boxes...
gonna check the build date on our Excursion! My van has a reman tranny in it from Ford so I assume it has no diode

Thanks for the education fella's
I bet they had the wiring off the side of the trans because they already ohmed the solenoids...just a guess
With a 7.3 excursion with 138K I would not be afraid to install a new 4r100 and go on with life.
If you want to sell that truck I know a few dozen people looking for one cheap! LOL
 
#11 ·
With a 7.3 excursion with 138K I would not be afraid to install a new 4r100 and go on with life.
If you want to sell that truck I know a few dozen people looking for one cheap! LOL
Haha. I can't sell it, atleast not for cheap. I have close to $13k tied into it. I ordered the pigtail you posted above. I'm going to test the solenoid and if it comes back bad then I'm driving it to get a new transmission installed.
 
#12 ·
Your still coming out ahead, 4x4 ex 7.3 with 138K worth about 18-20K here in Denver

Is your truck a 4x4?
I may be interested in your old 4r100 if you end up replacing the whole thing. I have a 01 Van I want to convert to 4wd and would be willing to pick up the old 4r100 to rebuild and use in my conversion
 
#14 ·
Oh it will be getting a full rebuild, I have a friend and we do them ourselves
I cannot use a case /builder that has had water in it
I vote turn his in as the core and sell me yours!

Keep us posted!
 
#18 ·
Im sure he meant if the solenoid pack checks out then he can verify it is the diode
The diode looks like a one way clutch when all assembled and goes in place of one inside the trans
The 4r100 had them from "2001 model year (July, 2000) and left production in March, 2001"
When rebuilding one of those ditch the diode and install normal one way clutch
Which is why I would not mind having a 138k mile 4r100 as a builder core I will do a full rebuild and one step closer to 4x4 van
 
#20 ·
Ok so I tested the OHM resistance on the solenoid pack. Below are the results.

Solenoid B- 21
Solenoid A- 21
TCC Solenoid (on-off)- 14.8
TCC Solenoid (PWM)- 14.8
Coast clutch solenoid- 21
Electric pressure control solenoid- 7

I also tested the OHM resistance on the spare trans that I have sitting in my garage and the OHM resistance read higher on every one, I'll list them below.

26
26
24
24
23
8

Suggestions?
 
#23 ·
You have done a good job diagnosing the issue, now its time to R&R trans
I would get a NEW trans instead of a rebuild, unless you trust your rebuilder alot and they have a good warranty.
You want a FULL REBUILD not some open it up replace the diode and some soft parts throw it back together and charge you $2500.....
 
#24 ·
I wish i had better news. This is all but guaranteed to be a failed mechanical diode.

I would get a NEW trans instead of a rebuild,
Where would you get a new trans? Ford hasn't built a 4r100 since 2004.
 
#25 ·
Re manufactured instead of soft rebuild is all I am getting at sorry if my terminology is not perfect.
As you know people get ripped off at trans shops all the time, they pay for a rebuild when all they really get is "issues addressed & road tested" no valve body work, just the basic gaskets and bands, new converter....road test pay full price in case there are call backs

You want to be an informed consumer, new is not correct term and the term remanufactured is so loosely used just make sure its fully rebuilt and correctly by a reputable builder. This hopfully includes ALL updates, valve body updates and new solenoids
Auto trans rebuild is either a happy renew for the vehicle or the beginning of a nightmare for the customer

http://www.trucktrend.com/how-to/tr...bulletproff-ford-4r100-transmission/#photo-09
 
#26 ·
I was quoted $2,950 for a rebuilt transmission, that's before taxes of course. The builder said it's a 450hp set up and with an upgraded converter the internals are good up to 650hp. It carries a 3 year/100,000 mile warranty. I've called a handful of transmission shops and this is the best warranty I can find available that's somewhat local (within a 4 hour driving radius).
 
#27 ·
Came across a rebuilt transmission from a 2001 F250. The truck belongs to a friend of a friend. It was stolen 6k miles after his 4R100 was reconditioned. He has paperwork to prove it was reconditioned. I may go that route. Build date on his transmission is "1K05" so November 5, 2001?
 
#28 ·
If the trans was rebuilt it almost certainly does not have a mechanical diode. Any rebuilder worth his salt knows to scrap a mechanical diode when he comes across one. You can't buy replacement mechanical diodes, but everywhere that sells transmission parts has a kit to replace the diode with a sprag type one way clutch.
 
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