Neutral Safety Switch problem with R154 swap in my OBDII SC400
02-25-14, 08:20 AM
#17
you guys don;t need to worry about the hesitation I feel it all the time, its slight in lower gears you can notice it if you are paying attention and only if you are slightly on the throttle. If you push down more on the pedal though the auto ecu will allow you to bang through the gears with no holdback. its only when you are only a little on the tps and even then It's not that bad took me a while to notice it.
so basically it wont slow you down when you gun it, but it does make for some soft shifts at lower speeds around town. I would not let that bother me with going manual at all no one should mind the ecu pulling timing for a second when you are going slow anyways.
so basically it wont slow you down when you gun it, but it does make for some soft shifts at lower speeds around town. I would not let that bother me with going manual at all no one should mind the ecu pulling timing for a second when you are going slow anyways.
02-25-14, 08:22 AM
#18
Driver School Candidate
Thread Starter
Join Date: Oct 2011
Location: CA
Posts: 17
Likes: 0
Received 0 Likes
on
0 Posts
Since my research led me on a wild goose chase, here are some conclusions:
Refer to the wiring diagram here:
https://www.clublexus.com/forums/per...up-lights.html
The ECU doesn't care if power goes to pin 7 (Park) on the neutral safety switch.
It does expect power to pin 9 (Drive) to activate the ignition and fuel maps. I used power from the pin 4 wire and hardwired it to the pin 9 wire and the reverse switch. The reverse signal is then fed to pin 8 (light blue wire).
You also need the transmission Shift Lock ECU, located in the shift console. Only the main connector needs to be attached to the main wiring harness under the console. I machined out he center section of the plastic shift console mounting bracket, to get rid of the automatic shifter, but retained the shift lock ecu mounting bracket and center console mounting points.
The main start permissive comes from the center wires (pins 5 and 6), as shown above. I just connected them together. The ECU will always allow the engine to crank, just like the old days.
I chose to remove the NSS connector completely and hardwire all necessary connections with solder and heatshrink tubing and tape it all up and put in inside a wire channel for reliability.
I hope this helps.
RC
Refer to the wiring diagram here:
https://www.clublexus.com/forums/per...up-lights.html
The ECU doesn't care if power goes to pin 7 (Park) on the neutral safety switch.
It does expect power to pin 9 (Drive) to activate the ignition and fuel maps. I used power from the pin 4 wire and hardwired it to the pin 9 wire and the reverse switch. The reverse signal is then fed to pin 8 (light blue wire).
You also need the transmission Shift Lock ECU, located in the shift console. Only the main connector needs to be attached to the main wiring harness under the console. I machined out he center section of the plastic shift console mounting bracket, to get rid of the automatic shifter, but retained the shift lock ecu mounting bracket and center console mounting points.
The main start permissive comes from the center wires (pins 5 and 6), as shown above. I just connected them together. The ECU will always allow the engine to crank, just like the old days.
I chose to remove the NSS connector completely and hardwire all necessary connections with solder and heatshrink tubing and tape it all up and put in inside a wire channel for reliability.
I hope this helps.
RC
02-25-14, 03:09 PM
#20
Driver School Candidate
Thread Starter
Join Date: Oct 2011
Location: CA
Posts: 17
Likes: 0
Received 0 Likes
on
0 Posts
It's described in post #31 here:
https://www.clublexus.com/forums/per...-lights-3.html
The loaded condition fuel map activates when the car is in D. I believe it is the cause of the driveability problem described at anything but WOT.
Examining the trans wiring diagram, you will see that the D wire from the NSS passes through the Shift Lock ECU, before going to the Engine Control Module. So I have mine connected.
No test drive at this point.
https://www.clublexus.com/forums/per...-lights-3.html
The loaded condition fuel map activates when the car is in D. I believe it is the cause of the driveability problem described at anything but WOT.
Examining the trans wiring diagram, you will see that the D wire from the NSS passes through the Shift Lock ECU, before going to the Engine Control Module. So I have mine connected.
No test drive at this point.
02-26-14, 10:01 AM
#22
Driver School Candidate
Thread Starter
Join Date: Oct 2011
Location: CA
Posts: 17
Likes: 0
Received 0 Likes
on
0 Posts
That comes directly from the '99-'00 SC400 Wiring Diagram. I'm pretty sure '97-'98 non-VVTi cars have the same trans wiring.
Last edited by RandC; 02-26-14 at 10:04 AM.
02-26-14, 12:29 PM
#23
Rookie
Join Date: May 2009
Location: Canada
Posts: 52
Likes: 0
Received 0 Likes
on
0 Posts
Good to know
Keep us updated on your progress, I am really curious how this will turn out.
While using D, the ECM will constantly send and receive signal from the solenoid inside the transmission in order to simulate 1-4 or 1-5 gear in your car. The engine RPM and transmission gear needs to match. Failure to get any signal feedback will trigger a code.
I believe that is the main the reason why most people just use leave the car on neutral when doing a manual swap.
Keep us updated on your progress, I am really curious how this will turn out.
While using D, the ECM will constantly send and receive signal from the solenoid inside the transmission in order to simulate 1-4 or 1-5 gear in your car. The engine RPM and transmission gear needs to match. Failure to get any signal feedback will trigger a code.
I believe that is the main the reason why most people just use leave the car on neutral when doing a manual swap.
02-26-14, 12:58 PM
#24
I just can't see there being 2 fuel maps and one activates in park and one in drive. many who do the swap leave it jumped in neutral and it gets fuel and spark just fine, there are no drivability problems except when the ecu wants to shift, and making it think it is in D will not solve the hesitation when you reach the speed the ecu wants to shift the auto at (even though its not there), cause if anything in D it will try and tell the trans to shift so that should cause the hesitation also, leaving it in neutral or park should be the way to avoid the shift points but believe it or not its always there.
the auto function on toyota ecu's is mostly seperate than the main ecu functions, meaning the ecu will always run the car under all conditions no matter what the trans is doing. for example on the LS400 the auto ecu is not even part of the main ecu, its seperate. in the early 90's and on the sc400 they started combining the 2 into the main ecu.
the only thought I had for getting around this issue is some of the older ecu's have a WOT switch or kickdown switch, and if you jump 5v to that it may think you are WOT and therefore not pull timing on shifts, but I have not tested it and it would only work for 92-94 ecu's if it even works.
also the main inputs for the ecu wanting to shift are the speed sensor and the tps position, so those could be places to look to solve that.
the auto function on toyota ecu's is mostly seperate than the main ecu functions, meaning the ecu will always run the car under all conditions no matter what the trans is doing. for example on the LS400 the auto ecu is not even part of the main ecu, its seperate. in the early 90's and on the sc400 they started combining the 2 into the main ecu.
the only thought I had for getting around this issue is some of the older ecu's have a WOT switch or kickdown switch, and if you jump 5v to that it may think you are WOT and therefore not pull timing on shifts, but I have not tested it and it would only work for 92-94 ecu's if it even works.
also the main inputs for the ecu wanting to shift are the speed sensor and the tps position, so those could be places to look to solve that.
Last edited by Ali SC3; 02-26-14 at 01:04 PM.
02-27-14, 08:35 AM
#25
Driver School Candidate
Thread Starter
Join Date: Oct 2011
Location: CA
Posts: 17
Likes: 0
Received 0 Likes
on
0 Posts
Good thoughts! I wasn't looking at it from the standpoint of engine control at the shift points.
I also was wondering why the trans lock signal is only active when the transmission is in Drive, but not 4, 3, 2, 1. It makes more sense that it controls torque converter lockup, not fuel map.
It looks like I'll be doing a bit more surgery on my wiring harness...
I also was wondering why the trans lock signal is only active when the transmission is in Drive, but not 4, 3, 2, 1. It makes more sense that it controls torque converter lockup, not fuel map.
It looks like I'll be doing a bit more surgery on my wiring harness...
02-27-14, 10:13 AM
#26
that is absolutely correct, in drive it will enable torque converter lockup and if its not working the overdrive light will blink at you when in D.
auto trans normall locks torque converter when the coolant temp is too low (right after cold starts), which is why it appears to have rougher shifting until the car warms up, that basically toyota's way of not allowing the torque converter to wear while the trans fluid reaches operating temp. It also locks it when cruising in overdrive so on long trips on the highway your trans fluid doesn't keep on heating up for no reason as you do not need the torque converter to be working unnecessarily if you are cruising. If this lockup is not working you could exceed the cooling ability of the trans fluid and radiator and then the trans fails.
again you sort of see how all the trans stuff is based on what speed you are going and the tps input, and sends signals to the solenoids on the trans at the speeds when switches are supposed to happen.
I am starting to think that this cannot be turned off from happening on the auto ecu, as in if you were going 20mph in neutral it would still pull timing for a shift you just would not notice it cause you are not accelerating.
I am still hoping there is some magical way to get around it, but honestly as I said earlier it is not really that noticeable, and when you want to go fast and push the pedal down the problem is not even there.
Now if it hesitated while making a WOT pull, then we would have all been angry and really been motivated to solve the problem.
auto trans normall locks torque converter when the coolant temp is too low (right after cold starts), which is why it appears to have rougher shifting until the car warms up, that basically toyota's way of not allowing the torque converter to wear while the trans fluid reaches operating temp. It also locks it when cruising in overdrive so on long trips on the highway your trans fluid doesn't keep on heating up for no reason as you do not need the torque converter to be working unnecessarily if you are cruising. If this lockup is not working you could exceed the cooling ability of the trans fluid and radiator and then the trans fails.
again you sort of see how all the trans stuff is based on what speed you are going and the tps input, and sends signals to the solenoids on the trans at the speeds when switches are supposed to happen.
I am starting to think that this cannot be turned off from happening on the auto ecu, as in if you were going 20mph in neutral it would still pull timing for a shift you just would not notice it cause you are not accelerating.
I am still hoping there is some magical way to get around it, but honestly as I said earlier it is not really that noticeable, and when you want to go fast and push the pedal down the problem is not even there.
Now if it hesitated while making a WOT pull, then we would have all been angry and really been motivated to solve the problem.
Thread
Thread Starter
Forum
Replies
Last Post
1999Gs300
Lexus Audio, Video, Security & Electronics
4
07-21-04 09:05 PM
