Archived 99, 2500 4x4 Auto Stuck in 1st & Reverse

[BrookeSmith]

I have a 99 2500, 4x4 with 82K miles. The automatic transmission only goes into 1st and Reverse. This was an instant failure, however I did notice the transmission was getting to be reluctant to go into second gear with a light thottle. Heavy throttle and it was fine.

I dropped the pan, looks good, replaced the Governor sensor and pressure solenoid, adjusted bands and I have the same issue. No check engine light. I have a deep pan and have serviced the transimission on 30K intervals. When the lever is in 1st, the transmission locks in 1st. When in D or 2, the trasmission 1st/Reverse band is not locked. The throttle return spring was disconnected. I reconnected it and still have the same issue. This is my primary mode of transportation. I pull two trailers and do some 4x4'n.



Any ideas what the problem might be? Also, if I need to replace the transmission, I would like to upgrade the clutches and TC. Looking for advice.



Brooke

 

[zstroken]

Pull the relay in the fuse panel under the hood. It is something like Powertrain or something. Make sure you have 12V at the pin of the relay. WHen you pull the relay you should get 3rd gear only. You will still have Reverse. Are you sure you have first gear only?? Sure it isn't second? If you have first gear only electronically you are holding the governor solenoid closed. I had this issue, and the wiring harness on the just above the VB connector was shorted. If you can answer the questions about the relay being pulled it will give me some more info to help.



Being locked in first when in manual first is normal. Unlocked in 2nd and drive is normal. Manual 1st applies the reverse band, which holds the drum from spinning.

 

[BrookeSmith]

I will look into the Relay issue this afternoon.

My max speed is about 25mph with the selector in D. I will post the test results tomorrow. Thanks for the fast response!

 

[BrookeSmith]

Removed the Relay, 3rd gear only

zstroken,

Took your advice and removed the transmission relay. I do have power to the relay. Also, the truck had reverse and 3rd gear only. Any new ideas? I put the relay back in and restarted. It had 1st gear only. I do not hear or feel the shift from 1st to 2nd.

 

[zstroken]

Well with the relay in and you having first gear, that says that your govenor solenoid should be working, it is closed not allowing you to build any governor pressure which is what runs the transmission thru the gears. By pulling it you remove the power to the transmission, so you have no louckup, OD, and the govenor solenoid stays open, which is why you have 3rd gear only. Leave the relay out. Start the truck, go to neutral, and immediately go to manual first, you should have first gear, drive, shift to second, you should have second gear, the shift to third, you should be able to go between 3rd and 2nd, you will not get 1st again unless you go to neutral again for about 5-10 secs and bleed off the govenor pressure. IF the above is true you have an electronic problem. Something is holding the governor solenoid closed. I would look for shorted wires. If you ahve a service manual you can check the resistance on all 3 relays and check the wiring somewhat in between with a meter. Lockup and OD should be about 30 ohms. I think the govenor solenoid should be about 4-6 ohms.

 

[Rammin On]

Sounds to me like you need a new output shaft speed sensor

 

[zstroken]

Wouldn't that throw the transmission into limp mode, which would put him in Drive?? I think prior to 2000 you could have a transmission code, with no MIL light. I could be wrong though. The times I have seen a bad output sensor, the transmission would go into limp.

 

[BrookeSmith]

I will pick up a DRB tonight and look for hidden transmission codes. I have not seen the MIL light up. I will also try the Neutral to 1st-2nd-3rd test as well. I hope for the transmission speed sensor, I have already replaced the differential speed sensor. According to the manual, the transmission control computer can use the vehicle speed sensor, however, maybe it's not.



Thanks for the support!

 

[Rammin On]

The output shaft speed sensor doesn't always light the mil ... nor does it always throw codes ... but you can view its operation with a scanner or DRB. I've replaced many that were causing the same symptoms as you described ...

 

[BrookeSmith]

I scanned the PCM and ECM with no codes noted.



When I tried the Neutral to 1st, 1st-2nd, and 2nd to D, the transmission remained in 1st gear.

I will measure the resistance of the speed sensor tonight. Also, I will look at the throttle control cable.

 

[BrookeSmith]

Rammin On,



How can I check the speed sensor functionality with a scanner?

 

[zstroken]

YOu need to use a snap on code reader, or a DRBIII. The neutral -1, 1-2,2-3 test should be done with the relay out. If you have all 3 gears, then something is grounding the Govenor solenoid. It could be the PCM, it could be the internal wiring harness on the VB, it could be external to the trans. It also could be the speed sensor, the times I have had a bad speed sensor I always saw I think code p0500, but that threw it in limp, this was on 2001 and newer though. The 99 is slighltly different PCM wise. It could also be the wiring to the speed sensor. The scanner at autozone won't display the output sensor status. It needs to be diagnostic software for a laptop, a snapon 2500, or a DRBII from a dealer. You might be best off to take it to a dealer and let them scan it.

 

[BrookeSmith]

Zstroken,

Thanks for saving me $280. I was going to pick up a new scanner. I borrowed a friends older scanner last night.

I bought a transmission speed sensor today and will install it tomorrow night. I also crawled underneath a 2001 truck at the dealership and noted a different spring orientation for the transmission throttle position cable. Thanks for hangin in there! I have enough time tonight to try the new spring location found on the 2001.

 

[BrookeSmith]

Zstroken,

I removed the transmission control relay and was able to shift from N to 1st to 2nd to D without problem. I will be installing the transmission speed sensor tonight. If that does not work, I hate to say this, go to the dealer for diagnosis.

 

[zstroken]

All that is telling you is that mechanically the transmission can shift. It could be a speed sensor, but I have always see that throw it into limp. You might park the truck on a hill raising the back end of the transmission when you change the sensor, it will help minimize the mess.

 

[BrookeSmith]

It was the Speed Sensor!

Good news and bad news,

The new speed sensor fixed the transmission, the bad news was the old one had a bunch of metal filings on it, thus decreasing the signal it could send to the PCM.

I will start saving! Do you know of anyone installing a separate, oil cooler in-line transmission filter? I see that BD has one for sale.

 

[zstroken]

I wouldn't worry about it if it is just fines. That isn't a big deal. chunks though then you have a problem. Rammin On was correct. Learn something new everyday.

 

[tshields]

This may be the simplest idea, but check your battery connections. happened to me a couple of years back. Was explained if there was a drop in the voltage or a variance enough to confuse the computer, the transmission would not shift properly. so after the posts were cleaned from the corrosion I was back on the road with no problems

 

[Rammin On]

Glad you got it fixed. zstroken is right - fine fuzz on the sensor is no biggie. Chunks are a different issue. Life is good!