5-speed A750 trans won't shift in to 5th gear. (2 Viewers)

[MongooseGA]

"Disconnected, cleaned it up some,"
I assumed and didn't you also write somewhere. The connector (wire housing block) had some signs of contamination inside?

The shop did tell me as much. It could have just been crusty pink residue on top of the connector, but we pulled apart all 3 on top of the trans and they all looked very clean. The shop did apply dielectric grease to all 3.

Interesting that it's a low fixed price and quick turnaround. Makes me think there's a common failure component like an electrolytic capacitor or cracked trace or something cheap and easy to replace.

This is my thought as well. I'll ask the guy some questions tomorrow and try to get a better understanding of what all is involved.

 

[MongooseGA]

Picked up the ECM. He repaired some solder joints on it. Put it back in the truck, issues persist.

Wtf.

 

[Bisho]

IIRC, there was a trans issue on here recently that was caused by a bad wheel speed sensor. Have you checked them? On my Fusion app I can call up all four and see if they are all the same.

 

[Dirt J]

IIRC, there was a trans issue on here recently that was caused by a bad wheel speed sensor. Have you checked them? On my Fusion app I can call up all four and see if they are all the same.

That was for the 4-speed but might also be applicable?

Linky

 

[MongooseGA]

IIRC, there was a trans issue on here recently that was caused by a bad wheel speed sensor. Have you checked them? On my Fusion app I can call up all four and see if they are all the same.

I did pull a speed sensor code when I hooked it up to TS at the trans shop. At the time I suspected it may have just been a low battery thing, but this is a good thought that I can look further in to. Since clearing the code that day, it hasn't returned on the dash. But I'll hook up TS again and see if there's something there.

 

[MongooseGA]

View attachment 3755035
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View attachment 3755036

This is what it gave me at the shop. I'm about to hook TS up to it now and see if those C codes are still there.

 

[Dirt J]

Per pages AT-4 and AT-5 of the FSM, there are 2 speed sensors on the trans case (not at the wheels). Did the parts cannon hit those in its initial volley?

 

[MongooseGA]

Per pages AT-4 and AT-5 of the FSM, there are 2 speed sensors on the trans case (not at the wheels). Did the parts cannon hit those in its initial volley?

I replaced one of them on the trans this Summer before going to CRockies. It's the one that the speedometer wiring hooks up to.

 

[Dirt J]

So that's the output one. Reading in the FSM it says the other one is the input one and controls shift points.

 

[Dirt J]

Edit: Check DI-418

 

[MongooseGA]

Edit: Check DI-418

Very helpful, thank you. Looking for a .pdf download of the full FSM right now.

 

[Dirt J]

Very helpful, thank you. Looking for a .pdf download of the full FSM right now.

PM incoming. I don't think I have your #.

 

[2001LC]

Any other DTC (codes) not mention. Even before no 5th?
Any dash warning lights inop, on or flashing?
Are brake lights working and on, only when pedal pressed?
Tip: First 3 second when IG key turn to on. System self test. All warning lights come on.

 

[MongooseGA]

Any other DTC (codes) not mention. Even before no 5th?
Any dash warning lights inop, on or flashing?
Are brake lights working and on, only when pedal pressed?
Tip: First 3 second when IG key turn to on. System self test. All warning lights come on.

The only codes I've been aware of (recently) were the P0771 and the DTC codes I requoted just a few posts above. Note: I never threw any readable codes on my ScanGauge, and I had the ABS/VSC/BRAKE lights on the dash when this first arose. The lights and no-5th-shift started at the exact same time as far as I could tell.

Idiot lights went off and stayed off the rest of the day after clearing, only returning after the truck got cold again. Say, first start up of the day they'd present.

It wasn't until I hooked up TS to the truck that I was able to read any codes at all. And, when driving the truck home from the trans shop, it threw idiot lights for ABS/VSC/Engine (not BRAKE any longer). None of these lights have returned since my drive home from the shop.

Yes, brake lights work properly. Idiot lights on the dash when I first put the key in, then they disappear when I turn the engine over.

 

[MongooseGA]

Loading up my parts canon now. I have 2 of the OEM trans speed sensors in my cart, now looking at the wheel speed sensors. I would almost always just default to OEM parts here, but my canon balls are not as big as they once were. Do we think the aftermarket sensors in the $30 range may be sufficient? Or this is one of those things where it really needs to be Toyota? I see kits of all 4 sensors for under $100.

 

[LJE]

Loading up my parts canon now. I have 2 of the OEM trans speed sensors in my cart, now looking at the wheel speed sensors. I would almost always just default to OEM parts here, but my canon balls are not as big as they once were. Do we think the aftermarket sensors in the $30 range may be sufficient? Or this is one of those things where it really needs to be Toyota? I see kits of all 4 sensors for under $100.

I'd suggest maybe a little more investigation first in order to more accurately aim that parts cannon? Seems like you could run some electrical resistance check on those wheel speed sensors?

 

[Dirt J]

There's a resistance test for the input sensor in the FSM. I'd start with a visual unplug/plug back in check. Physical connection could be loose, not fully engaged.

 

[MechE30]

I don’t have anything technical to add, just a moral boost: Keep your chin up. It’s just a machine, there is a reason for the issue and a solution, you will find it.

 

[MongooseGA]

I'd suggest maybe a little more investigation first in order to more accurately aim that parts cannon? Seems like you could run some electrical resistance check on those wheel speed sensors?

Stop making sense.

My ADHD is killing me here. I can read everything about how to physically replace the parts but as soon as it comes to diagrams, I shut down.

There's a resistance test for the input sensor in the FSM. I'd start with a visual unplug/plug back in check. Physical connection could be loose, not fully engaged.

I found it on the 2nd page after. Looks like an easy enough test.

I don’t have anything technical to add, just a moral boost: Keep your chin up. It’s just a machine, there is a reason for the issue and a solution, you will find it.

This bitch better straighten up before she turns in to a Powerstroke Excursion.

 

[MongooseGA]

Interestingly, at the moment there are none of the previous DTC codes, but the P0771 persists.