nv_blazin_trd
2️⃣ Bronze
- Joined
- Dec 14, 2018
- Messages
- 10
- Reaction score
- 10
I'm making this post to help anyone that has this problem. Very little info out there so I am sharing what I found and fixed.
*** I would start with the A.D.D module before the T-case shift motor. Less chance of messing up the timing and it is much easier. ***
So last night I put my truck into 4H to pull into a driveway with huge snow drifts, well when it shifted into 4x4 it had a super hard clunk - didn't think much about it and shut the truck off with it still in the 4H position. Came back out to it several hours later to drive home and the 4x4 high just kept flashing - shifted it to 2wd and same thing.
I couldn't get any response from the 4x4 system.
No codes to go off of when I connected my toyota scan tool.
Once I got it into the shop I started troubleshooting.
I thought the problem was in the T-case shift motor so I started there. I disconnected the electrical connector, removed the 3 12mm bolts, removed the rubber bushing between the shift motor and the t-case housing, then I removed the 7 screws on the bottom of the shift motor.
I then separated the shift motor plate from the housing ** be extra careful if you are doing this - there are three gears and three pins that will fall out - ALSO you have a lead frame with 4 pins that is very fragile so be extremely careful not to break the lead frame***
Once the gears are removed I inspected everything to make sure the gears are okay, I then removed the shift motor housing and pushed the shift fork all the way in to put it in 2wd. You can verify that it is in 2wd by moving your front driveline by hand and then see if you're rear driveline reacts at all - no movement of the rear driveline = 2wd.
I used a 12v battery to test the shift motor - to test both directions just reverse the polarity. I then soldered the leads since they have a weak connection from factory. I used a multimeter to test the 4h and 4L switches - once everything was tested I then reassembled the shift motor. The bottom plate has a red gear *** this red has a timing mark - line it up***
The bigger gear with the spring loaded backing ring is the gear that moves the shift fork - there is a timing mark on the shift motor housing. You must line up the "467" timing mark on the gear to the housing timing mark. ** it is okay if it is one or two teeth off just depends on your shift fork just get it between the "467" and the "268" timing marks as close to the "467" as possible***
Once this gear is in you can then install the other two gears and pins. You must hold these gears in place with a skinny screwdriver or your fingers - it is very important you have the gears nice and tight before installing the bottom plate. Then install the bottom plate without loosing gears and keeping the lead frame from breaking. Then install your 7 screws, reinstall the rubber bushing, install the three bolts, and then reconnect your electrical connector.
If your problem is here then no need to do this next part - for me this was not the problem area.
I moved onto the A.D.D module on the front diff. This is the same concept as the t-case shift motor but it moves a gear sleeve back and forth to engage and disengage the front diff. It is accessible without dropping the diff like some people claim. Drop your skid plate then it is on the passenger side of the clamshell. Disconnect the electrical connection, removed the breather, remove the 4 mounting bolts, and then remove the A.D.D module **be careful there is a fork on this module so you will have to use some angles to get it out without breaking it** Once removed, remove the 5 screws and take off the plastic cover. Here you will test the motor with both polarity and then test your switch - if all is good - solder the pins for the motor (this is a weak factory setup and causes problems). Make sure your fork moves back and forth. Then crawl back under the truck and reach into your diff - there is a gear sleeve in there - make sure this moves freely without freezing up. If all is good reassemble your A.D.D module, clean off the old rtv on the module and the diff housing, apply new rtv to the module and then reinstall the A.D.D module. ****note that when the sleeve is all the way to the p/s it is in 2wd, when it is to the D/S that is 4x4. I moved my shift fork to 2wd before reassembling the A.D.D module. Do not force it because the gears are plastic. Move the sleeve to 2wd and then reinstall the A.D.D module. Make sure your fork is in the groove on the sleeve and then reinstall your 4 bolts, breather tube, and the electrical connector. Test your 4x4 - this worked for me - the A.D.D sleeve got froze up and taking it apart freed it up.
If you test and inspect these components I'm sure you will find something that is causing the flashing. The hardest part of doing this is getting you timing right. Sorry there are no picture - didn't think of taking any while I had everything torn apart.
Good luck!
In theory you could test all of the electrical components though the connector but you would have to find a wiring diagram and a pin out - which I was unable to find.
*** I would start with the A.D.D module before the T-case shift motor. Less chance of messing up the timing and it is much easier. ***
So last night I put my truck into 4H to pull into a driveway with huge snow drifts, well when it shifted into 4x4 it had a super hard clunk - didn't think much about it and shut the truck off with it still in the 4H position. Came back out to it several hours later to drive home and the 4x4 high just kept flashing - shifted it to 2wd and same thing.
I couldn't get any response from the 4x4 system.
No codes to go off of when I connected my toyota scan tool.
Once I got it into the shop I started troubleshooting.
I thought the problem was in the T-case shift motor so I started there. I disconnected the electrical connector, removed the 3 12mm bolts, removed the rubber bushing between the shift motor and the t-case housing, then I removed the 7 screws on the bottom of the shift motor.
I then separated the shift motor plate from the housing ** be extra careful if you are doing this - there are three gears and three pins that will fall out - ALSO you have a lead frame with 4 pins that is very fragile so be extremely careful not to break the lead frame***
Once the gears are removed I inspected everything to make sure the gears are okay, I then removed the shift motor housing and pushed the shift fork all the way in to put it in 2wd. You can verify that it is in 2wd by moving your front driveline by hand and then see if you're rear driveline reacts at all - no movement of the rear driveline = 2wd.
I used a 12v battery to test the shift motor - to test both directions just reverse the polarity. I then soldered the leads since they have a weak connection from factory. I used a multimeter to test the 4h and 4L switches - once everything was tested I then reassembled the shift motor. The bottom plate has a red gear *** this red has a timing mark - line it up***
The bigger gear with the spring loaded backing ring is the gear that moves the shift fork - there is a timing mark on the shift motor housing. You must line up the "467" timing mark on the gear to the housing timing mark. ** it is okay if it is one or two teeth off just depends on your shift fork just get it between the "467" and the "268" timing marks as close to the "467" as possible***
Once this gear is in you can then install the other two gears and pins. You must hold these gears in place with a skinny screwdriver or your fingers - it is very important you have the gears nice and tight before installing the bottom plate. Then install the bottom plate without loosing gears and keeping the lead frame from breaking. Then install your 7 screws, reinstall the rubber bushing, install the three bolts, and then reconnect your electrical connector.
If your problem is here then no need to do this next part - for me this was not the problem area.
I moved onto the A.D.D module on the front diff. This is the same concept as the t-case shift motor but it moves a gear sleeve back and forth to engage and disengage the front diff. It is accessible without dropping the diff like some people claim. Drop your skid plate then it is on the passenger side of the clamshell. Disconnect the electrical connection, removed the breather, remove the 4 mounting bolts, and then remove the A.D.D module **be careful there is a fork on this module so you will have to use some angles to get it out without breaking it** Once removed, remove the 5 screws and take off the plastic cover. Here you will test the motor with both polarity and then test your switch - if all is good - solder the pins for the motor (this is a weak factory setup and causes problems). Make sure your fork moves back and forth. Then crawl back under the truck and reach into your diff - there is a gear sleeve in there - make sure this moves freely without freezing up. If all is good reassemble your A.D.D module, clean off the old rtv on the module and the diff housing, apply new rtv to the module and then reinstall the A.D.D module. ****note that when the sleeve is all the way to the p/s it is in 2wd, when it is to the D/S that is 4x4. I moved my shift fork to 2wd before reassembling the A.D.D module. Do not force it because the gears are plastic. Move the sleeve to 2wd and then reinstall the A.D.D module. Make sure your fork is in the groove on the sleeve and then reinstall your 4 bolts, breather tube, and the electrical connector. Test your 4x4 - this worked for me - the A.D.D sleeve got froze up and taking it apart freed it up.
If you test and inspect these components I'm sure you will find something that is causing the flashing. The hardest part of doing this is getting you timing right. Sorry there are no picture - didn't think of taking any while I had everything torn apart.
Good luck!
In theory you could test all of the electrical components though the connector but you would have to find a wiring diagram and a pin out - which I was unable to find.
