No Downshift, RABS light on?

[BossHog]

I have been having issues with the e4od in my '91 since I got it. It wasn't shifting, had the tranny rebuilt, still wouldn't shift. After replacing the FIPL myself it was finally able to shift. However, it will not downshift. I adjusted the FIPL or TPS or whatever you want to call it and that helped with some of the soft or early shifting problems I was having but still no down shift. I pulled out the VSS on the tranny and it looked fine, cleaned it and the connections off. Is there a way for me to test the VSS?

I didn't think this had anything to do with downshifting but the rear ABS light has been on continuously as well. I've read that FIPL, VSS, and 3rd brake light can all affect e4od shifting but I haven't been able to find an article that addresses no downshifting at all. Before I go and replace every sensor in the truck I'd like to know if there is a good to start solving this issue.

Has anybody seen this issue before. Like I said it's a '91 7.3 with duallies, crew cab XLT lariat. Runs great, no downshift. Thank you for any help!

 

[Nero]

So you come to a stop and it's still in overdrive? Or are you trying to get the shift kick down when accelerating hard?

 

[quickster]

What color is the tps on the pump? If it's a black one iirc you need to change to the gray one. Look up the article on setting the voltage for the tps. Maybe Trackspeeder will see this.

 

[BossHog]

So you come to a stop and it's still in overdrive? Or are you trying to get the shift kick down when accelerating hard?

Once it shifts into od or any gear for that matter it will not shift down at all. If I put it in P, 1 or 2 I get my lower gears back. It just won’t do it automatically.

 

[BossHog]

What color is the tps on the pump? If it's a black one iirc you need to change to the gray one. Look up the article on setting the voltage for the tps. Maybe Trackspeeder will see this.

It’s black but I bought it brand new. I read that the newer ones all come black but they’ve fixed whatever was wrong with the old black ones. I have a gray one that I pulled out of an e-350 van but have no idea how old it is. I couldn’t find a new gray one anywhere.

 

[Nero]

So what happens if you come to a stop and you do not manually downshift?

 

[BossHog]

So what happens if you come to a stop and you do not manually downshift?

It stays in the last highest gear. So if it shifted into 2nd before coming to a stop it stays in 2nd when I stop. If it shifted all the way up to 4 or OD it stays in that gear. The problem is if I'm traveling at highway speed and slow to make a turn or attempt to pull a hill I have to do it in high gear which sucks. Otherwise I have to shift to park ad then it starts back in 1st. I looked for a kick down cable but I'm pretty sure its all electronically shifted so it has to be a sensor. I don't think it's the transmission computer though because it has no problem shifting up at all, and the OD works just fine.

 

[Nero]

That's super strange. Just wanted to get a better understanding as what's going on. Do you have any codes?

 

[BossHog]

That's super strange. Just wanted to get a better understanding as what's going on. Do you have any codes?

I haven't pulled any since I had the rebuild done. The transmission shop that did my rebuild pulled a speed sensor code but they said they replaced the speed sensor on the rear diff and that didn't change anything. I talked to another shop that said the speed sensor on the transmission (I think the VSS) could be tested to make sure it's working mechanically. I pulled it out and it looked good to me (but what do I know?) For whatever reason my transmission doesn't know when the truck is slowing down, or it is not able to make the shift. I'm almost certain it's not mechanical as I just had the tranny rebuilt. It also shifts manually with almost no issues and then goes through all the shifts pretty easily when I accelerate. So it has to be a sensor or maybe the TECA? I guess I will pull codes again and see what's going on.
Do you know if the rear ABS light would affect shifting at all?

 

[samshrout]

I haven't pulled any since I had the rebuild done. The transmission shop that did my rebuild pulled a speed sensor code but they said they replaced the speed sensor on the rear diff and that didn't change anything. I talked to another shop that said the speed sensor on the transmission (I think the VSS) could be tested to make sure it's working mechanically. I pulled it out and it looked good to me (but what do I know?) For whatever reason my transmission doesn't know when the truck is slowing down, or it is not able to make the shift. I'm almost certain it's not mechanical as I just had the tranny rebuilt. It also shifts manually with almost no issues and then goes through all the shifts pretty easily when I accelerate. So it has to be a sensor or maybe the TECA? I guess I will pull codes again and see what's going on.
Do you know if the rear ABS light would affect shifting at all?

Hey did you ever figure out what the issue was? My e350 is having the same symptoms & it'd be a huge help to know how you solved yours. Thanks.