'94XLT auto tranny problem

[juggernaut2874]

My '94 XLT won't shift into overdrive. Fluids have recently been changed and at the proper level. Also there seems to be some sort of "road noise" (similar to off-road tires) when I accelerate. 170,000 miles on engine and tranny with no leaks. Any ideas??

 

[MrShorty]

3-4 shift on these is computer controlled. I would start by determining if the problem in the EEC-IV controls or not. I know I've posted detailed instructions for doing this a handful of times before. Start by pulling codes and go from there.

 

[juggernaut2874]

My code scanner gives me code 566 and 629 which basically tell me there is a problem with the 3-4 shift solenoid. Correct? I do not have any fuses blown. How do I fix it?
I first noticed the overdrive problem after having a garage remove and replace the fuel pump and sending unit. After they reconnected their wires, they kept blowing fuses in the distribution panel and the explorer would quit running. Could they have screwed up some wiring by shorting something out?

 

[juggernaut2874]

The 566 and 629 are KOEO codes. My truck did not have any CM codes stored. How can I verify if the solenoids are good to go? How much resistance should they have?

 

[Glacier991]

There is an A4LD Valve Body Rebuild Diary, lotsa good info in it, including resistances. Search for it... I was the poster, so you can search by my name as well.

 

[juggernaut2874]

Thanks Glacier and Shorty, I'll let you know what I come up with.

 

[MrShorty]

A KOEO 566 refers to the 3-4 shift solenoid, 629 refers to the torque converter lockup clutch solenoid. I would look at the thing that those two solenoids share in common, namely a common power supply (do you have a wiring diagram?). Any chance they've simply come unplugged at the transmission?

 

[Glacier991]

I'm with Mr. Shorty.... anytime you have both solenoids coming up with codes it is 99% likely electrical in nature.

 

[juggernaut2874]

I've done continuity tests on on the 3-4 solenoid and TC solenoid where the wires go into the PCM. I checked between pin 51 (3-4 shift) and pin 37 (red wire) and got an open. Checked pin 53 (TCC) to pin 37 and got an open also which is why I am getting KOEO codes 566 and 629.
Now I'm doing continuity checks on the wires going back to the solenoids. So far all have ohm'ed out fine.

Am I correct in assuming then that both solenoids are open or is there something else?

 

[BrooklynBay]

As was previously mentioned, check the connector on the driver's side of the transmission. It has 3 wires. This connector goes to the 2 internal solenoids inside of the transmission.

 

[juggernaut2874]

Problem fixed! When the mechanics were installing the new fuel pump and sending unit, they must have done it with the battery still connected. They ended up burning a wire completely through causing the open in the circuit and KOEO codes 566 and 629. Glad it didn't set the whole wiring harness on fire. Soldered the wires back together and... boom baby I have overdrive back!!

Thanks Glacier, Mr.Shorty , and Brooklyn for the advice.

 

[Glacier991]

Thanks for the follow-up. That helps others!