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Discussion Starter #1
Ok I'm in need of some help. I bought a 1995 supra that the previous owner tried to do some upgrades. Yes they were a good thought but I'm at a loss. Car wont turn over with key , I can jump relay and it will turn over. They had door handles shaved , they put TVs in steering wheel and passanger dash, tried to put a throttle trigger NOS system and attempted to put MSD programmer. Anyways , I took most of it off, replaced all relays, new starter, new fuses, the keyless Fob sounds like its popping door locks . Anyone think of what I'm missing ??? I've got all technical manuals from toyota .
 

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handy with the steel
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Sounds like antitheft relay.

Try locking the car, then unlock from the passenger side.
 

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Discussion Starter #3
I can't no door locks or handles on exterior . I can lock on inside no problem. But still does change the results. Let me ask you on this particular model I've been told that if the hood , hatch , or door are open it wont crank ? I cant see anything in schematic that would lead me to think this is true?
 

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handy with the steel
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That's not true, you can start with all of that stuff open...at least mine will, anyway.

Pretty sure it's the antitheft relay that's getting you. Find it and jumper the contacts, then try starting. If it turns over, that's your problem. If not, start looking elsewhere. The circuit between the ignition barrel and the starter relay is very simple so there isn't much to troubleshoot, UNLESS the previous owner did some weird stuff like a remote start or turbo timer.
 

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Discussion Starter #5
If you could see how bad of attempts they made to modify stuff. I pulled probably 15 to 29 feet of wires they had trying to wire aftermarket stereo and the keyless entry isnt the stock one . I'm thinking about trying to find an entire console , chassis, and engine bay wiring harness just cause I dont want to put the money I'm planning on putting in it and have it go up in smoke cause of someone's half ass attempts you know.
The TDS relay is the one on passanger side kick panel right ? If I'm reading the location and wire schematic right.
 

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handy with the steel
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Actually I was mistaken earlier, there is no theft deterrent "relay". The theft deterrent ECU has an output that it uses to complete the circuit going through the starter relay. Check the pin i've boxed in below. With a multimeter, check continuity between this pin and battery negative (chassis ground). If you have continuity, then the theft deterrent ecu is "allowing" start. If you do not have continuity, then the theft deterrent ecu is not allowing start.

247201
 

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Discussion Starter #7
Ok key on theres no continuity on start relay , same with key off . How do I bypass the TDS ? The schematic shows I should have ground through W-B WIRE 4 if I dont have ground there that means its cut out starter right and I just need to get wire 1 and 4 to ground to bypass right?
 

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handy with the steel
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To bypass the antitheft ecu, you would ground out the pin I boxed above. It goes to connector IB3-pin 8 on TT cars, and IB2-pin 6 on NA cars. This should be a wire colored L-O (light blue with orange stripe maybe?? Check TSRM for color code).

If it were me, I would cut the "ecu side" and splice it to a ground point.


Before that though, it would be beneficial to check that you are getting 12V+ on the starter relay from the ignition switch. The clutch switch or P/N switch could also be holding you out, although this is less likely I think. You will need some help to check for 12V bc you will need to have the meter set up and watching it while someone is turning the key.
 

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Master Shit Fixer
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My money's on the simple Clutch Start Switch (think horses, not zebras), but you're going to have to troubleshoot the circuit that CDSaints posted, step by step.

If you're not getting +12v at pin 1 of the starter relay while trying to start the car, then your problem is on the right side of the diagram. I'd start there.
 

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Discussion Starter #10
Ok I replaced both clutch switches and brake switch when I first got car. The brake lights started working after I did that. The reason i replaced clutch switch was cause one was broke. And I checked switches this morning to make sure they were working properly and both are.
 

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Discussion Starter #11
Thanks guys for all the help , I finally got to the TDS , and wanted to update yall on what I found. I pulled it out of car open TDS and its smoked . Wire completely burned out of board .
 

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Thanks guys for all the help , I finally got to the TDS , and wanted to update yall on what I found. I pulled it out of car open TDS and its smoked . Wire completely burned out of board .
Congrats on the find. Will you be replacing it or just bypassing it? Hope you get her started soon!
 

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I pulled it out of car open TDS and its smoked . Wire completely burned out of board.
Probably from the PO's crappy wiring. Do you want to try to have the TDS repaired?
 

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Discussion Starter #14
To bypass the antitheft ecu, you would ground out the pin I boxed above. It goes to connector IB3-pin 8 on TT cars, and IB2-pin 6 on NA cars. This should be a wire colored L-O (light blue with orange stripe maybe?? Check TSRM for color code).

If it were me, I would cut the "ecu side" and splice it to a ground point.


Before that though, it would be beneficial to check that you are getting 12V+ on the starter relay from the ignition switch. The clutch switch or P/N switch could also be holding you out, although this is less likely I think. You will need some help to check for 12V bc you will need to have the meter set up and watching it while someone is turning the key.
Congrats on the find. Will you be replacing it or just bypassing it? Hope you get her started soon!
 

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Discussion Starter #15
Man she turned over for the first time since I got her with the key !! Now of course more issues lol. Now fuel pump wont power up. If I'm reading manual right , it doesnt get power till it starts but how do I prime system if pump doesnt come on. I went to diagnostic port under hood and jump fp to b but nothing I'm guessing pump is out and I cant find anywhere in trunk the ECU for pump it shows to have .
 

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handy with the steel
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Good job!

I'm less familiar with the fuel pump controls since I just pulled mine out and replaced it, but the very first thing is to start checking for 12V+ at the pump. Work your way back from there, using the wiring diagrams as a guide.

I'll take a look also when I have a minute and see if anything stands out.
 

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Discussion Starter #17
Ok awesome thanks. I just found where they ran a 12v wire from a toggle switch to the L-R wire in rear hatch area going to fuel pump. I just found FP ECU so I'm going to check power to ECU and go from there. But I'm guessing from them having that wire ran they probably burned up the fuel pump. I need to clean out fuel tank anyways so why not replace it now while I'm in there instead of on the side of the road lol. But if I'm missing something dont hesitate to tell me.
 

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handy with the steel
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Sounds like you're on top of it. I know there is a common modification people do to bypass the fuel pump ecu and bring 12V directly to the pump, so that may be what is going on with that wire.

12V Mod
 

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Discussion Starter #19
But if I'm not mistaken putting 12v to it full time when switch is on , wont that burn up the pump on most vehicles. I know it's a 12v pump but I'm not sure if they didnt leave it running. But if I jump FP-B in diagnostics and pump is good it should kick on even if just for a second right? Every other vehicle does. I really do appreciate all the help on this car. My shop is open to any of yall if yall are ever on east Texas area.
 

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handy with the steel
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According to that article I linked, the consensus is that the 12V mod will marginally reduce expected lifespan, but nothing to worry about. With that said, it sounds like you might have surpassed that point.

Easiest way to check is to rig up a battery directly to the pump and see if it comes on....I suggest you stick a fuse inline if possible though, those wires can heat up FAST and you'd be messing around right above the gas tank.

BTW we're practically neighbors. I'm in Lafayette LA 🙋‍♂️
 
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