*One more mkiii that won't crank =(

[chezpo0f]

I would love to be able to read the diagnostics on my Supra... Where can I get a scanner for the mk3? Most of the mechanic shops around here all turn me down when I tell them it's a 90 model... They only go back to 2000 or 1995

Btw, normally I would not just throw new parts at my car. I've been working on my celica since I got it over 15 years ago and never took it to a shop... Me and my dad rebuilt the engine. But when it comes to the electronics side I just don't like to mess with it. But with this problem, its been going on over a year and I have gotten desperate.

Thanks again for all the input guys.

[El Supracabras]

That's not exactly what I meant by diagnostics but they do make a scanner for the 7mgte diagnostics= a multi-meter can tell you whatever the computer has to say. Learning how to use one will save time, money and improve the enjoyment factor of owning a mostly electronic controlled 20+ year old sports car. The correct diagram is posted in the 3rd post of your thread.
If you can rebuild an engine, you got this. An electrical circuit is hardly different then an oil passage circuit or a coolant circuit. If something causes resistance (dirt/corrosion/defective part), the flow will decrease until the fluid is no longer able to flow where it needs to go and eventually something will suffer. If there was a huge hole (broken hose,stuck t-stat=broken wire, defective electronic part) then the fluid would not make it where it needs to go at all because it will flow out of the new hole instead or may not flow at all because it's path has been disrupted and now something will quickly suffer. For an electrical circuit to exist electrons must make the loop exactly as the oil or coolant. Think of the battery and charging system as the oil pan and pump, the oil starts and eventually returns to the pan, electrons start and return to the battery. The alternator keeps the pressure up. Measuring electricity is like measuring the level, pressure and condition of your oil. I really hope that kinda helps.

[chezpo0f]

Well, does anyone know how easy it is to get to the neutral start switch? I'd like to start checking for power there. In other words... Can I get to it from the top under the shifter console or am I gonna have to pull the transmission lol? If that's the case i'll definitely start at the ignition switch and work my way down =p

I'll check my chilton book when I get home... but who knows how helpful that will be, getting excited at work with a few new ideas to get this baby running again

Thanks

[El Supracabras]

Should be on the trans wherever the shifter linkage is. Follow the cable. Never had a problem w/ one on a supra but pretty sure its easy enough to get at with the car jacked up off the ground. Wire colors are on the schematic provided by btwilson86 earlier. Your manual should have a decent enough explanation of how to test it.
I would suggest to check for voltage at the starter solenoid first while someone else turns the key to start. This will eliminate the starter as the problem w/o having to remove it. If there is adequate voltage there, the starter may be defective and would need further testing. If no voltage there, move back to the neutral switch check for voltage going into the switch,
if no voltage there, move back to the relay check for voltage at the relay, then the ignition switch etc. etc. follow the schematic backwards from the starter to the battery.
When you find a component (that is in the correct position to) receiving voltage but NOT letting it out and you are sure you have checked it properly, you have found a problem. Repair it and check again. If you find voltage going in AND coming out properly but not making it to the next component down the line you have found a bad wire. Locate,repair and check again.
The theft deterrent system opens the ground to the starter relay. If you still think it is the problem you can bypass it completely by cutting the ground wire from the relay and grounding the relay straight to the chassis. This removes the starter cut out from the system completely (watch where you park).

Boy, how many posts do I need to make to not be stock on my avitard anymore? Go into it armed with the right info and attitude and you will driving it again in no time. Happy headaches!

[btwilson86]

You should be able to check the neutral start switch from it's electrical connectors. They're on the intake side of the engine, running down next to the firewall. The switch itself isn't very difficult to remove, the exhaust pipe may get in the way though (it's been a long time since I removed one)