1998 HDJ80 with 1HDT - Refresh (1 Viewer)

[cahill]

Interesting, on my 97 80 series the rheostat affects the cluster and radio/climate control. I haven't tested it on the lx450 in a while and can't recall if it is different.

Edit: I doubled checked the rheostat function on both of mine ( the LC and LX) - they are the same. The affect the brightness of the cluster/speedometer and the radio. I didn't notice a change in brightness of the clock or climate controlls. The climate control lights on the lx do seem dimmer than the lc

 

[logicbyondreaso]

Another setback.
As I pulled the parts from underneath the 80 I noticed a few things I missed in the darkness. The valve body will need to come apart to inspect and replace the following components.

1. A half of the modulator valve plug on the upper valve body had fallen out. I don't think this caused my shifting issues as the other half is retained in position by the retainer key and spring force. But maybe contributed. This will need to be replaced. Part number 90339-04045

2. Valve body gaskets (35433-36021 and 35434-36021) will need to replaced. Along with the lower body cover gaskets (2 x 35435-36020)

Broken valve plug:

Supposed to look like this:

Where it came from: modulator valve.

Broken/missing gasket.

Broken gasket.

 

[logicbyondreaso]

My thought process was confirmed correct. Once the valve body was on the bench with good lighting - I verified the valve is still in correct place due to the key as seen in image below. I will disassemble when replacement gaskets arrive so it can be assembled same day.

Yellow - retainer key
Red - where it sheared

This little key is holding the entire valve in place along with spring force.

 

[logicbyondreaso]

Gaskets and replacement valve parts came in. Spent an evening cleaning and assembling the valve body. Some dirt built up but not enough to worry. However, someone has been in here before....
First sign was a number of bolt lengths did not match what the FSM had. I assumed some error might exist in the FSM since I have seen it before. I measured every bolt and documented the position it came out of. In the end I took a tally and realized they were just scrambled. During assembly every bolt was put into the correct location per FSM.
The second sign was the valve body gaskets. Not OEM. It took a while to clean them off the plates but I wanted to ensure a smooth finish and no leak-by.

 

[logicbyondreaso]

Upper and lower valve bodies were separated. Every valve was removed and neatly organized/labeled.
Again, aftermarket gasket. Some buildup but nothing to worry about.
All check balls were accounted for, retaining pins in correct locations, and all parts present.

 

[logicbyondreaso]

I inspected every valve for damage, or signs of severe wear. Some buildup on a couple of the valves but overall in good shape. The photo below is not a chip but a collection of fine metal dust. I think my magnet pen magnetized the valve and the dust was attracted.

Replacement valve parts for the modulator valve. I took this valve body apart to replace the plug that was found broken. Decided to replace the valve, spring, plug and retainer. Still available from Toyota for a few dollars.

Metal dust accumulation

All parts organized, labeled, inspected, and checked against FSM. Springs and retainers, check balls, etc. all have specific lengths, diameter, and colors.

The valve body plate had a lot of the gasket material stuck to it along with staining from the passages. I took ATF and a very fine buffing pad to remove it all.

 

[logicbyondreaso]

Once every component from the valve bodies was accounted for they were cleaned thoroughly and inspected for any cracks or failures. Some of the check ball seats had wear but not concerning amount. I could not find new valve body halves or the plate new or else I would have replaced them.

 

[logicbyondreaso]

Final assembly. Every bolt was checked for length and position via FSM. Torqued to spec. Ready to go in.
Replacement solenoid harness is arriving today so I can try to button everything up.

 

[logicbyondreaso]

Accumulators removed and new o-rings installed. Old were hard.

The C2 accumulator is straight forward to remove - apply compressed air and it pops out. Turn down you air pressure to prevent injury. I loosed my retaining bolt/washer enough to allow the accumulator to pop out but not fall out. This helps a lot in keeping control of the process.

B0 and B2 accumulators share the same port where you apply air pressure. Likely one will come out before the other. Service the one that comes out and then put it back in place and use a bolt/washer to prevent it from coming out. Then apply air pressure again and service the second accumulator.

 

[logicbyondreaso]

Wiring harness arrived. Part number 82125-36010. I used a multimeter to confirm the pins were the same to the harness I removed.
The valve body is heavy and the center support gaskets are loose in position until valve body is tightened. I used a little petroleum jelly to hold them in place. Also the accumulators have springs that need to be installed and the throttle cable must be connected. Because of these factors, I rigged up a jacking system that would allow me to carefully and precisely install the valve body. It also served as a resting/thinking device. Stainless M6x1.0 threaded rod and some nuts.
Bolt lengths were confirmed against the FSM and installed/torqued. Filter and then the pan. Seal packing 1281 per FSM. Part number 00295-01281
Finally, I replaced the homemade or "field repair" fusible link with new. Part number 90982-08267
I will let the FIPG cure and then fill up the transmission with new fluid. 10qts came out during this job.
Then I will test to see if all of this work did anything to improve the shifting.

All of the existing gasket material was removed after photo was taken.

 

[logicbyondreaso]

I finally had time to fill up the transmission with fluid, check for leaks and adjust the ATF level.
Taking it on a test drive I quickly learned that the 2-3 flare is still present with little to no change from before the valve body job. Manual shifting was smooth.

The next step was to read the FSM in more detail. I stumbled across something in the electrical and transmission manuals that I did not see before. I missed it because there was an earlier fully hydraulic A442F that most references discuss.
The A442F (electronically controlled) has a transmission control module with part number 89530-60170. One of the inputs for this module is the throttle position sensor (TPS). I followed the FSM for testing it and found that it was not correctly adjusted. Way off. Looks like someone had it off at some point and did not follow the FSM for installation. Once I adjusted it to spec and test drove the problem was gone. No more flare and the transmission runs really well.
For those who have the electronic A442F and are experiencing the shifting flare - check out your TPS setup as it may very well be the culprit.

I have read a few posts that mention a discrepancy in wiring labeling of VC and VA in the transmission manual. These statements are (possibly) confirmed by the 1HZ, 1HD-T, 1HD-FTE Engine FSM RM617E. Page FU-108 and 109 show the following and are assumed to be correct.

Another difference found between the engine and transmission manuals is correct throttle position sensor (TPS) adjustment voltage.
Transmission Manual: 0.96 volts
Engine Manual: 0.6 +/- 0.025 volts

The TPS on my truck looks original and because heat can impact the potentiometer functionality over time - I am going to replace it with new and make more accurate adjustments. New part number 89452-36010

 

[duece71]

I finally had time to fill up the transmission with fluid, check for leaks and adjust the ATF level.
Taking it on a test drive I quickly learned that the 2-3 flare is still present with little to no change from before the valve body job. Manual shifting was smooth.

The next step was to read the FSM in more detail. I stumbled across something in the electrical and transmission manuals that I did not see before. I missed it because there was an earlier fully hydraulic A442F that most references discuss.
The A442F (electronically controlled) has a transmission control module with part number 89530-60170. One of the inputs for this module is the throttle position sensor (TPS). I followed the FSM for testing it and found that it was not correctly adjusted. Way off. Looks like someone had it off at some point and did not follow the FSM for installation. Once I adjusted it to spec and test drove the problem was gone. No more flare and the transmission runs really well.
For those who have the electronic A442F and are experiencing the shifting flare - check out your TPS setup as it may very well be the culprit.

I have read a few posts that mention a discrepancy in wiring labeling of VC and VA in the transmission manual. These statements are (possibly) confirmed by the 1HZ, 1HD-T, 1HD-FTE Engine FSM RM617E. Page FU-108 and 109 show the following and are assumed to be correct.

Another difference found between the engine and transmission manuals is correct throttle position sensor (TPS) adjustment voltage.
Transmission Manual: 0.96 volts
Engine Manual: 0.6 +/- 0.025 volts

The TPS on my truck looks original and because heat can impact the potentiometer functionality over time - I am going to replace it with new and make more accurate adjustments. New part number 89452-36010

View attachment 3469347

This is very helpful. Is the TPD also referred to as the “kick down” cable? Would you describe “shift flare”? Great thread.

 

[duece71]

This is very helpful. Is the TPD also referred to as the “kick down” cable? Would you describe “shift flare”? Great thread.

Sorry TPS, spell check can be weird.

 

[logicbyondreaso]

This is very helpful. Is the TPD also referred to as the “kick down” cable? Would you describe “shift flare”? Great thread.

TPS and kick down cables are two different parts.
TPS sits on top of the injection pump (assuming you have an electronically controlled transmission)
Kickdown cable is connected to the injection pump and transmission via cable. It adjusts the pressure of shifts.

As for the flare - here is one of many discussions on it. Essentially there is a jump in rpm between shifts. It does not immediately shift into next gear.

Transmission flare on 1-2 shift possible fix (A442F) - https://forum.ih8mud.com/threads/transmission-flare-on-1-2-shift-possible-fix-a442f.949634/

 

[duece71]

TPS and kick down cables are two different parts.
TPS sits on top of the injection pump (assuming you have an electronically controlled transmission)
Kickdown cable is connected to the injection pump and transmission via cable. It adjusts the pressure shifts.

As for the flare - here is one of many discussions on it. Essentially there is a jump in rpm between shifts. It does not immediately shift into next gear.

Transmission flare on 1-2 shift possible fix (A442F) - https://forum.ih8mud.com/threads/transmission-flare-on-1-2-shift-possible-fix-a442f.949634/

Ok, I have the A442F even though my HDJ81 is a 1990. I have a fairly large rpm drop when it shifts from 3 to 4 and am curious if this is the flare you are talking about. It accelerates in 3rd just fine until about 22-2300rpm and then the shift to 4 is noticeable by a drop of around 500rpm. Shifting is smooth just a noticeable drop in engine rpm. Thank you for the link.

 

[logicbyondreaso]

Ok, I have the A442F even though my HDJ81 is a 1990. I have a fairly large rpm drop when it shifts from 3 to 4 and am curious if this is the flare you are talking about. It accelerates in 3rd just fine until about 22-2300rpm and then the shift to 4 is noticeable by a drop of around 500rpm. Shifting is smooth just a noticeable drop in engine rpm. Thank you for the link.

Likely the torque converter is locking up.

 

[logicbyondreaso]

Video on TPS adjustment:

 

[logicbyondreaso]

An update on the A442F 2-3 flare and hard shifting problem - The TPS was the issue. Even though the one installed on the pump passed the FSM tests, it was defective. I replaced it with a new one, 89452-36010, adjusted to specification, and the problem vanished. The transmission shifts smooth and without any flaring between gears.
Before swapping in the new one, I bench tested it against the old. The old TPS was aged and showing that by almost double the resistance compared to the new one.

If anyone is having a shifting flare, and is fitted with a TPS, look at that first and consider replacing it if original. I rebuilt my valve body in search of resolving the flare issue but also had to due to a broken valve plug and valve body gasket.

While the 80 was in the garage I swapped out the old shocks/springs for OME stock height springs (2861/2862) and OEM shocks (48511-69435 and 48531-69486).
Next, I am going to replace the tires with Toyo Open Country MT 255/85R16.

 

[duece71]

I finally had time to fill up the transmission with fluid, check for leaks and adjust the ATF level.
Taking it on a test drive I quickly learned that the 2-3 flare is still present with little to no change from before the valve body job. Manual shifting was smooth.

The next step was to read the FSM in more detail. I stumbled across something in the electrical and transmission manuals that I did not see before. I missed it because there was an earlier fully hydraulic A442F that most references discuss.
The A442F (electronically controlled) has a transmission control module with part number 89530-60170. One of the inputs for this module is the throttle position sensor (TPS). I followed the FSM for testing it and found that it was not correctly adjusted. Way off. Looks like someone had it off at some point and did not follow the FSM for installation. Once I adjusted it to spec and test drove the problem was gone. No more flare and the transmission runs really well.
For those who have the electronic A442F and are experiencing the shifting flare - check out your TPS setup as it may very well be the culprit.

I have read a few posts that mention a discrepancy in wiring labeling of VC and VA in the transmission manual. These statements are (possibly) confirmed by the 1HZ, 1HD-T, 1HD-FTE Engine FSM RM617E. Page FU-108 and 109 show the following and are assumed to be correct.

Another difference found between the engine and transmission manuals is correct throttle position sensor (TPS) adjustment voltage.
Transmission Manual: 0.96 volts
Engine Manual: 0.6 +/- 0.025 volts

The TPS on my truck looks original and because heat can impact the potentiometer functionality over time - I am going to replace it with new and make more accurate adjustments. New part number 89452-36010

View attachment 3469347

The TPS is only on the 1-HDFT and FTE engines correct?

 

[OGBeno]

The TPS is only on the 1-HDFT and FTE engines correct?

Any HDJ8x vehicle with an automatic transmission.