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Car is all back together and ready for the track tomorrow..
@JWconeil Probably a little of both. The larger rear tires rub on hard dips but, so do the splitter skid pucks.
@Fin The OEM radiator is with the engineers now and they are building the files needed for the machines to make the first few for verification. Adding 1/8 NPT bungs so I (and whoever else may get one) can run addtnl sensors for things like water temps/water pressure.
Any chance they'll add a loop for the gearbox? I really like having the oil temperature stabilized as much as possible for the street. Running a larger cooler doesn't ensure the transmission is running at optimum temperature under less than track conditions. It would be plenty easy to block it off if you didn't want it.
Any chance they'll add a loop for the gearbox? I really like having the oil temperature stabilized as much as possible for the street. Running a larger cooler doesn't ensure the transmission is running at optimum temperature under less than track conditions. It would be plenty easy to block it off if you didn't want it.
No, not in the plans, It would add complexity of manufacture and an additional failure point. Having logged trans temps now for a while on and off track, and having spoke with smarter people than I about at WS thresholds i can say the fluid heats up and cools down very quickly on its own. Even when running a divorced set up with a separate cooler. Its in operating threshold from 90-225*. Above that is where you have to worry, not below. My car with an external cooler on a 50 degree morning takes about 3 min of idling to get up to 90* and will never drop below that on its own idling or driving. The transmission itself also holds heat extremely well. After warming up once in the morning the trans temps dont drop below 80f for the rest of the day, even with the occasional 3 hour wait between sessions.
Have you thought about running a Laminova cooler for this reason? You could gang it inline to the water system and have them stabilize each other. I have one off a old formula car had been poking around for a reason to use it. IMO this would not be it.
I live in sunny Socal so take it with a grain of salt. It may be an issue driving around somewhere much colder than here
Wow, I ran that dual core cooler on my old built S14's SR20. Paired with a Yashio factory radiator with A defi link monitor to show oil temp (and water temp) when the car was in motion. Sorry off topic but that image brought back memories lol No one appreciated the benefits of that Mocal unit. Again, thanks for documenting all this progress.
I know all about how long the gearbox stays hot. The absurdly low temperature they use for setting the level is witness to that. If it's 80F outside, you'd better be quick or you'll be over temperature before you get a chance to set the level. At 45F, it takes a while to get the gearbox into the prescribed range.
I am sure WS works over a wide range of temperatures, but I know well the gearbox limits choices when the fluid it cold. Even moreso on the 6 speed in the IS 350. There are lots of coolant/oil heat exchangers, it's just easier to use something akin to OEM to get the temperature optimized, and for sure the gearbox is most efficient when the oil is at a happy temperature.
So I loaded up the car this Thursday night for an early drive out to the track Friday morning. Woke up at 430am and fired up the ISF to pull it outta the garage and when i shifted into reverse it was the fimiliar hard clunk. WTF. I drove it up the street and cycled the battery kill but it would consistently throw the P0705 code again. So strange. I just replace the Neutral switch and set everything and it was working great when it was up in the air the day before. Well I had to pull back into the garage and swap all of my track stuff over to my NSX and ended up taking that instead.
Today I broke out the Electrical FSM and the Standard FSM and traced and voltage checked all of the wires. There was some mild confusion till I realized that the factory electrical diagram had the transmission signals in the pin out shifted one hole over. But other than that everything checked out. I traced each signal along circuit from its power source and didnt come up with any faults. The FSM's last remaining step is to replace the Transmission Control Module (TCM). I pulled it out and took the cover off to inspect for any damaged or fried components but i didn't see anything obvious. I would be surprised if this module went bad- but all signs it seems are pointing there (That is unless there is some really really sneaky hidden intermittent short somewhere in the loom that runs down the back of the engine.)
TCM is buried under all the engine looms in the engine bay and is responsible for sending the solenoid signals to the transmission and the CEL to the dashboard.
All of this check out in addition to reading voltage for each gear shift placement at all of the junctions. What I wasn't able to do is visually inspect all of the wires as they just disappear down a back hole of wires. I hope it doesn't come to that.
You can see from the electrical manual that power originates LH-IG fuse. I replaced this fuse with a new one to be safe. then it goes into the the park position selector (which is brand new) from there, depending on gear it pipes out to a junction connector where it branches the signal to the ECU and the TCM. Both of which read the appropriate signal on both side of the junctions at the ECU and at the TCM plug. I also replace their source fuses to be safe too. So basically the only thing i couldn't check was the TCM itself. But then again It wasnt throwing the code or being difficult when I was doing all the work today.
What do you guys think?
Also are all the TCM's the same for all years? Is it an ISF specific part? I'm reading mixed things when searching for one to buy.
Does this occur when only using the brake pedal ? And are the results the same using your gear shift override lock?
Suggesting the possibility if the brake pedal relay switch is acting up or not..
Also did you have to bend your shifter linkage arm to create clearance for the CF drift shaft bolts ???
Does this occur when only using the brake pedal ? And are the results the same using your gear shift override lock?
Suggesting the possibility if the brake pedal relay switch is acting up or not..
Also did you have to bend your shifter linkage arm to create clearance for the CF drift shaft bolts ???
No not when using the brake pedal. It happens randomly on start up, sometimes ill start the car and immediately there is no 'P' indicating that the car is in Park on the dash and it'll immediately throw a code. Sometimes the 'P' will be there but when i go and change it into reverse I get a harsh engagement and it does not display the 'R' or any consecutive gear position that is selected, this is not always followed by the cel and code. I believe that one time it happened when i was driving on the freeway on a long haul back from the track, I noticed it when i was about half way home, its possible that it did it on start up and didn't throw a code and i just didn't see.
I tested a theory yesterday and the dash display only shows P N R D when the ECU gets the correct signal, if I unplug the ECU connector responsible for the trans I don't get P D N R on the dash readout. This means that the signal isn't coming into the ECU when it happens (or its seeing multiple signals?). You can see in the electrical diagram i posted that Junction e73-e74 actually splits the signal from the Park Neutral switch to both the TCM and the ECU at the same time; without being able to test the TCM i'd have to assume that if there is a fault it's somewhere from the connector at the Neutral Switch to the e73-e74 junction, or the wires from the junction to the ECU and TCM. I suppose it could ALSO be either the TCM or the ECU but for some reason i'm having a hard time believing these have just gone bad. (I have seen it before, but yeah.) I am ready with my multi-meter the next time this happens I have separated the strands with zip ties and removed the cover to make probing the pins on the ECU, and junction easy when it does happens. That way ill be able to tell- if its happening and there are the correct signals on the correct wires present then the problem lays at the terminus module. I am seeing the TCM's at leaset go from $120-350 used, so its almost in the 'may as well' price range just to rule it out. I just need to know if I specifically can only use one from a 2008 isf or of they are interchangeable through all years. (similar to the steering ECU, they are listed by years but can be used interchangeably)
Yes, I did bend the shift arm to clear the carbon DS puck, I considered this to but there is a slotted hole on the shift linkage that i re-positioned so the shiftier stops and reads the appropriate gear in each of the positions in the shift box. Being an intermittent issue i just don't think that is it, but it may be worth a revisit.
I would also recommend opening the TCU and probing the back side of the connector where it goes into the board. It's possible a pin has grown tired and isn't making a good connection at the TCU connector. I had this problem with my Supra when it was about 10 years old, and it was a huge PITA to troubleshoot because all the wires checked out and all the components checked out. I ended up backshelling one pin to move the inner petal up and all has been well for the last 16 years. The connection supplies 5 Vdc to the throttle position sensor(s) and the MAP sensor. It was totally intermittent and temperature related.
Ok so it's been a little bit. I had some track events and spent a lot of my free time wiring and prepping another competition car I drive to get it ready for the season opener at CoTA in a month. The good news is that I was able to definitively figure out the transmission weirdness. I think I was mentioning above that the factor manuals for the most part are wrong when it comes to the ECU pinouts for the trans ECU and the Engine module. They are not hugely off but can vary by a couple pins. I looked at several different ones, including the online manuals from Toyota/Lexus and the Toyota/Lexus hard copies that I have in my garage. Both were off in some connectors by a pin or two Both are for my vin range specifically... very strange. I have never seen this happen before in a factory manual. Anyways this meant that I would have to verify everything for myself before starting; which added a substantial amount of time and complication to the trouble shooting.
First thing I did was understand where all the wires went, most of them snake through a few connectors and through a main junction connector where Lexus splits the signal. The main head scratcher here was that the signal that is split doesn't always send the signal out the other side of the connector it will even vary to which signal is being split... On occasion it will energise a terminal bus that will have a pin and wire returning the 12v of the same connector on its way to somewhere else in the bay, or worse yet energising multiple wires coming out both sides.. This is what took the longest to get my head around. I would rough sketch the connector layout then go through each leg of the circuit at the termination point.
After doing this I would verify the logic with the manual and get the connector names. I ended up making and refining some schematics to plot out the signal paths to identify and isolate probable problem areas. the final fix took a collective 20, maybe 30 hours, It's always slow going and you need to maintain laser focus on the task at hand until it's complete.. then you need to back out and get a 10000ft view to see how that info changes your diagnosis. It sucks but I was determined to get to the bottom of this. I just did not believe that the trans ECU would have just gone 'bad' out of the blue, and I REALLY didn't want to buy another one and have to reset the transmission shift parameters in Techstream and have it relearn just to get the same code to show back up.
After getting a good understanding of the way the ECU and Trans ECU were taking to the trans shift switch I started to gradually widen my scope from problem components to the harnesses themselves. I pulled the harnesses apart on the legs that i'd identified, everything checked out. When reading the selector live data with the techstream I was finding that the fault was caused when the car would see Reverse and another Shift signal at the same time, which is a parameter to throw the code.
At that point I could isolate it to something happening with the reverse circuit, not necessarily when it was in R but there was some confusion coming from the R bus pins in a terminal junction connector. I went into the electrical FSM and followed the path backwards through the harnesses from the reverse lights. This is when I was like "ohhhhh...." I noticed that there was a signal coming from the Main ECU Bkup wire at the termination of the lights. I assume this is for a "back up light busted" warning on the dash or something similar.
It all started coming together...
My theory.. the ECU(s) get a constant memory voltage from the battery. I'm postulating that this current was back feeding from the ECU- through the tail lamps- back to the under dash junction box- and back up the e73 connector where the factory splits the signal from the transmission selector. This junction has pins going to a common bus from A) The reverse lights B) The transmission ECU.. C) The Engine ECU D) The shift selector switch.. This meant that there was an errant voltage getting read by the transmission ECU (the one that throws the cel) as well as all the other common pins on this bus. This 12v from the back up lights likely coming from the engine ECU.. This all jives with the resistance I am seeing on that circuit. To test this I clipped and installed a switch on the wire going to the 'back up' lights from the e73 bus connector. sure enough when it was switched 'on' I would get the interference signal and engine code, and when switched 'off' all would be right with the world. So, in short, it wasn't a problem with the selector, fuses, ecu.. it was a problem occuring in the common bus; and when the car was running and in drive or whatever I was asking it to do the trans ECU would suddenly see this other voltage telling it the shift selector was in reverse and it would freak out and save itself.
Not wanting to mess around I removed the R signal completely from the e73 bus and ran it direct to both the transmission ECU (which like I said is responsible for throwing the code in question) and to the engine ECU. Now they both get clean signals exactly where they need to be. Problem solved.
I cannot imagine paying someone to diagnose this. It just would have been a nightmare bill or replacement parts that were completely unneeded. I glad I like to poke around and have an understanding of this stuff. At the moment I don't have reverse lights; NABD on a track car.. I'm going to eventually relay a signal, maybe from the floor shifter itself to power an electromagnetic relay to pop on the tail lights when I'm backing up.
After fixing the problem I drove the car to work for a week just to make sure, then headed to a track event at Chuckwalla raceway where I set a new Personal Best. There's some aero balance stuff I have found out, along with a few things I need to do to solve the fuel starvation the car sees on left handers over 1.3 sustained G's. Thats all going to have to wait for another post tho. Here's the PB video, enjoy!
Glad you found it, but it's pretty bizarre it worked for years, then failed requiring the intervention you did. It's also pretty bizarre the factory wiring diagrams are incorrect. I've never seen that, so I'd really like to know what isn't right and get it corrected. That's surprisingly simple with a TIS subscription.
This diagram shows a screenshot of the interactive diagram in TIS on the brake side first, then the rest of the TCU/ECM connections in the second. Can you point out what's not right?
Just did a quick check on E73 - that thing has a whole lot of connections going through it. Ignition coils, transmission position switch, cam position, crank position, and VVT sensors (all of them). Pretty busy place.
Ok, I think I figured out the "manual is wrong" part. I'm looking at the backup light circuit, and it isn't shown on the diagram with the ECM, TCU, and switch assembly. But it looks a lot like you've got two green wires on the B side and two green wires on the A side and they're all connected internally at E73/E74. I noticed there are a couple of massive junction blocks in these cars, one on each side. So the FSM simplifies the diagram, leaving out a bunch of stuff and making it seem it's incorrect because you're looking at the connector and looking at the diagram and saying these two things are not the same. Is that what you meant?
12-17-20, 04:45 PM
