93 Explorer A4LD, No OD!!!

[93TwotoneXLT]

Whew, it's been a long time since I have been on here(over a year). Hello all! Ok, I know that this is a well worn subject. I have searched the threads but have not seen a same situation as mine. I gave my X to my stepdad so he could have something reliable to drive until he retires. He has been driving the X for over a year and all was well until last night when he calls me telling me the radiator is leaking. I came and picked up the X to replace it at the shop I run(oh yeah, I am a service manager) and I noticed that I have no OD. Replaced the radiator under warranty then drove it to check overall tranny operation. Partial or full throttle, 1,2,3 shifts are great. Positive engagements, no slipping/flares. I DO have TCC lockup as well in 3rd. Tranny just won't shift into OD. Tried manual from D to OD as well, still no OD. Pulls fine in D or OD when pulling away from a stop. No check engine light. I have access to an NGS tester and checked for codes but none are stored/current. This weekend I am going to install a new throttle body as I also found out the factory one is starting to bind. I am going to adjust the bands but I am doubtful this will fix the issue. I also plan on checking the 3 wire connector at the tranny for the correct inputs. I have a few questions for the gurus on here. 1. OD being computer controlled, if the solenoid were bad, it would throw a code and trigger the check engine light, right? 2. I have read about a plugged solenoid screen, is it accessable by just dropping the pan or do I have to remove the valve body too? 3. If there is anything else I should be checking for, could you please inform me of it? Thanks to all for any help/reply's.

 

[MrShorty]

1. OD being computer controlled, if the solenoid were bad, it would throw a code and trigger the check engine light, right?

Depends on how the solenoid failed. My experience with some of these solenoid codes (like the 566 that would apply to your 3-4 shift solenoid) is that they only throw a code for either a full open in the circuit or a short to ground. If the solenoid fails in such a way that it still has electrical continuity, the PCM on these won't know it has failed. There are also no other "inputs" to the PCM to verify if the transmission responded to the command to shift into 4th gear. The next couple of steps for checking the electronic control of the 3-4 shift that I like to use are A) put a voltmeter across the solenoid, then enter output state test, and see if the PCM can talk to the solenoid. then B) a road test with the voltmeter still hooked up to see if the PCM chooses to tell the transmission to shift.

2. I have read about a plugged solenoid screen, is it accessable by just dropping the pan or do I have to remove the valve body too?

I'm pretty sure you have to drop the valve body, also.

 

[93TwotoneXLT]

Thanks Mr. Shorty for the reply. What's funny is that my stepdad has not even noticed that the overdrive is not working. I only knew about it when I drove it to work to install the radiator. I'll update later when I get a chance to check all of the electrical connections. Anyone with who has had this specific issue and what they did to fix it is welcome to educate me. Thanks.

 

[BrooklynBay]

The overdrive servo could be dried out, and leaking. A band adjustment might help determine if the band is broken or out of adjustment. The PCM uses various sensors such as the TPS, VSS, and the MAF to determine when to shift into overdrive. Are the tires the stock size?

 

[93TwotoneXLT]

Brooklyn Bay, Tires are stock. Truck is completely stock except for the custom purple front fender. I hooked our shop NGS tester and monitered all of the sensor inputs and all are within spec. I have 1,2,3 and TCC lockup, just no OD. I am going to dig into it a little bit over the weekend. Thanks for the reply.