SC300 general transmission question.
11-04-20, 02:03 PM
#16
the parking brake light will come on if the brake fluid reservoir is low or the connector going to the sensor on the reservoir is unplugged.
Or if the parking brake is on, OR if it has adjusted so many times its maxed out and the light stays on cause of the too far adjustment keeping it on.
on a drift car where you yank on the e brake constantly and it has all those other brake issues, I would guess its maxed out and pads/rotor are destroyed already.
tach has nothing to do with the transmission, that would be the speedo. Tach comes from ignitor, so either the cluster or the wiring in the car body harness or car engine harness is the issue.
usually is an issue on a swap or with the cluster if stock. sounds like someone really played with your car so I wouldn't rule anything out.
Or if the parking brake is on, OR if it has adjusted so many times its maxed out and the light stays on cause of the too far adjustment keeping it on.
on a drift car where you yank on the e brake constantly and it has all those other brake issues, I would guess its maxed out and pads/rotor are destroyed already.
tach has nothing to do with the transmission, that would be the speedo. Tach comes from ignitor, so either the cluster or the wiring in the car body harness or car engine harness is the issue.
usually is an issue on a swap or with the cluster if stock. sounds like someone really played with your car so I wouldn't rule anything out.
11-04-20, 02:26 PM
#17
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sooo i looked at the breaks today and saw the cables in the rear are completely shredded so im assuming thats whats causing the light on the dash hahaha just more I need to fix but hey its mine now. Also i was talking about the speedo not the tach sorry man the speedo doesn't work.
11-04-20, 06:37 PM
#18
Ali, you never disappoint me with your extensive knowledge and troubleshooting. I have and still do remain a student when reading your posts digging into complex issues and history 
ChaseMcCla, other than seconding all of Ali's posts above, the speedometer gets its signal from the transmission's 3-wire VSS (vehicle speed sensor) or with an older cable-driven R-series transmission from a Marlin Crawler VSS adapter that you screw onto it (unless you happen to swap in an OEM Toyota VSS unit). That signal is what can be modified by a Yellr Yellowbox to account for final drive ratio and tire overall diameter changes so as to be made accurate again once you benchmark against some accurate GPS speed reading device (Garmin, TomTom or your phone with an app).
Since these cars are getting old and little issues can come up, another thing is that your speedo gauge motor can stick a bit (the same can happen with your tach gauge motor). Tanin Auto Electronix can fix those issues when you send your cluster in to them. First however I would rule out any issue with your transmission's VSS sensor and/or with the chassis harness wiring between it and your instrument cluster's chassis side connector.
As Ali said in his last posts, your SC300 seems to have been messed with a lot by the previous owner who drifted it so I would go through the entire car to make sure everything is working correctly. Hopefully there was no messing with the transmission VSS wire loom and connector leading to the transmission but if so it's not going to be difficult to sort out.
If there has been extensive wiring modification especially to the engine harness I kind of recommend picking up any used 1990's Toyota engine wiring harness from which you can strip out and filter a lot of OEM Toyota high quality wires of varying gauges and colors with which to do proper soldering and heat shrink repair work.
ChaseMcCla, other than seconding all of Ali's posts above, the speedometer gets its signal from the transmission's 3-wire VSS (vehicle speed sensor) or with an older cable-driven R-series transmission from a Marlin Crawler VSS adapter that you screw onto it (unless you happen to swap in an OEM Toyota VSS unit). That signal is what can be modified by a Yellr Yellowbox to account for final drive ratio and tire overall diameter changes so as to be made accurate again once you benchmark against some accurate GPS speed reading device (Garmin, TomTom or your phone with an app).
Since these cars are getting old and little issues can come up, another thing is that your speedo gauge motor can stick a bit (the same can happen with your tach gauge motor). Tanin Auto Electronix can fix those issues when you send your cluster in to them. First however I would rule out any issue with your transmission's VSS sensor and/or with the chassis harness wiring between it and your instrument cluster's chassis side connector.
As Ali said in his last posts, your SC300 seems to have been messed with a lot by the previous owner who drifted it so I would go through the entire car to make sure everything is working correctly. Hopefully there was no messing with the transmission VSS wire loom and connector leading to the transmission but if so it's not going to be difficult to sort out.
If there has been extensive wiring modification especially to the engine harness I kind of recommend picking up any used 1990's Toyota engine wiring harness from which you can strip out and filter a lot of OEM Toyota high quality wires of varying gauges and colors with which to do proper soldering and heat shrink repair work.
11-05-20, 01:08 PM
#20
--your gauge needle motors may be sticking.
--trouble with the chassis sub-harness or connector on it going to the transmission VSS under the car.
--you may actually have a Supra MKIII W58 transmission which has a mechanical speedo drive stock. A Marlin Crawler VSS adapter can solve this but the larger issue is that version of the W58, IF you have it, is even weaker than an SC/MKIV W58 and definitely should be replaced with an R-series transmission if it's already got internal issues prompting the need for a rebuild.
Inspect the W58 transmission first from the outside. It is easy to tell if it's an SC, MKIV or MKIII spec W58. The MKIII type will have an aluminum center sandwich plate rather than the steel of the later versions and it will have that mechanical speedo drive and a separate sensor for ABS on its casing that we do not use with SC's.
11-05-20, 03:18 PM
#21
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thanks so much for another useful and fast reply i cannot thank you and sc enough for the help you have already givin me. TOday i took out the interior so i could dye the carpets and center console. but tomorrow il borrow a buddys jack and stands are really get under the car. to check hopeing the needles stuck! thanks guys and il lyk
11-05-20, 05:01 PM
#22
Thanks Kahn, I just break alot of stuff so then I have to fix it lol. Likewise you never disappoint with your extensive swap and chassis info, I don't know anyone who has payed attention to the level of detail you have and I always enjoy the read.
Chase, I think we need some pictures of stuff. probably didn't bother with the Vss or disconnected or its the older W58 as Kahn mentioned.. didn't even think of that one at all.
Chase, I think we need some pictures of stuff. probably didn't bother with the Vss or disconnected or its the older W58 as Kahn mentioned.. didn't even think of that one at all.
11-05-20, 09:42 PM
#24
Ali, I still feel I'm a novice at a lot of this even if I focus on a lot of details. I've learned so much from your posts even for projects I haven't attempted yet but your fundamentals and creative problem solving are always good in depth reads for me too. I always learn something new from your posts and knowledge 
I think you're onto something with breaking and having to fix things. It forces us all to learn new things and how to adapt creatively!
Chase, you're more than welcome-- and I'm with Ali on the need for some pictures to help identify what you're working with. You may yet have an issue to address with your cluster gauge motors (it's sort of common after this many years with SC's and other 90's Lexus vehicles and fixing it is common) but the easy potential things need to be eliminated first with pictures because of your car's history.
I think you're onto something with breaking and having to fix things. It forces us all to learn new things and how to adapt creatively!Chase, you're more than welcome-- and I'm with Ali on the need for some pictures to help identify what you're working with. You may yet have an issue to address with your cluster gauge motors (it's sort of common after this many years with SC's and other 90's Lexus vehicles and fixing it is common) but the easy potential things need to be eliminated first with pictures because of your car's history.
11-06-20, 06:40 AM
#25
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Ali, I still feel I'm a novice at a lot of this even if I focus on a lot of details. I've learned so much from your posts even for projects I haven't attempted yet but your fundamentals and creative problem solving are always good in depth reads for me too. I always learn something new from your posts and knowledge I think you're onto something with breaking and having to fix things. It forces us all to learn new things and how to adapt creatively!
Chase, you're more than welcome-- and I'm with Ali on the need for some pictures to help identify what you're working with. You may yet have an issue to address with your cluster gauge motors (it's sort of common after this many years with SC's and other 90's Lexus vehicles and fixing it is common) but the easy potential things need to be eliminated first with pictures because of your car's history.
I think you're onto something with breaking and having to fix things. It forces us all to learn new things and how to adapt creatively!Chase, you're more than welcome-- and I'm with Ali on the need for some pictures to help identify what you're working with. You may yet have an issue to address with your cluster gauge motors (it's sort of common after this many years with SC's and other 90's Lexus vehicles and fixing it is common) but the easy potential things need to be eliminated first with pictures because of your car's history.
11-06-20, 04:04 PM
#27
We would need some wider pictures than the ones above and at different angles to evaluate the transmission. I see your oil level sensor on the upper oil pan and I can make out what look like aftermarket solid/poly engine mounts... which would make sense for drifting but a set of 1997-2002 Supra MKIV stock OEM engine mounts would be a little kinder for all around street use. For mostly drift use they're probably fine to keep but I have not idea what brand and quality they are. I'd replace them with MKIV OEM personally.
11-07-20, 02:21 PM
#28
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will do i just got done redoing my interior and im stoked on it il get more pictures tomorrow for you guys im gonna borrow my friends jacks and jack and get them done for yas also evrything on the car is megans racing so i think im just gonna keep the bushings for now hahaha.
11-10-20, 10:00 AM
#29
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Hey guys I got under my car and noticed my trans doesn't have the plugs at the back of the transmission it doesn't even have openings for it so I'm assuming it's the w58 out of the mk3 supra meaning I'm gonna buy a used w58 that's actually good instead of rebuilding it. That aside I have a new issue I would love yalls help with my low beams and high beams work but only when the high beam is selected when it's in the low beam setting it doesn't work neither turm on same with auto light it just doesn't work the plate light turns on but the headlights don't, I checked the fuses but they all seem fine and the high beams turn on so idk lmk if yall have anything you can enlighten me with.
11-11-20, 01:32 PM
#30
I was afraid it might actually be a W58 from an MKIII Supra. Since it was used for hard drifting, even with an NA engine that abuse is probably the reason for it having some internal issues now. Since you'll be drifting as well I still recommend skipping even the SC or MKIV W58 and going right into an MKIII R154 (with a 1st gear thrust washer upgrade at least) or later tripod R154, AR-5, R150 or R155. All of them will be stronger, more upgradeable and better able to stand up to the abuse that comes with regular drifting. An SC or MKIV W58 against an NA engine is better for mostly street use honestly where it will last nearly indefinitely as Ali SC3 stated. But for drifting the stronger transmission is recommended especially since you've got to find a new transmission solution to replace the broken one anyway.
Yeah, I wouldn't bother with rebuilding the MK3 W58. Maybe someone can use it for parts to recondition another one for another build that's using a W58.
...
The low beam and high beam issue I'm not sure on. If you've checked all your relays then I'd start testing your crucial wiring going to the low and high beams and the bulb connectors themselves. Do you have the SC300/400 electrical wiring TSRM PDF handy?
Yeah, I wouldn't bother with rebuilding the MK3 W58. Maybe someone can use it for parts to recondition another one for another build that's using a W58.
...
The low beam and high beam issue I'm not sure on. If you've checked all your relays then I'd start testing your crucial wiring going to the low and high beams and the bulb connectors themselves. Do you have the SC300/400 electrical wiring TSRM PDF handy?
Last edited by KahnBB6; 11-11-20 at 08:53 PM.