I did my TPS adjust yesterday...I used the light thingy to set it. I noticed that if I thightened the screw down all the way, then begin to loosen it...first one light would go on, then a quarter turn later the second one would light up. I know that I need to in between one light and two...but within the range of that quarter turn where do I want to be??? Closer to the one light shutting off, OR closer to the second light turning on?

 

First of all ditch the light they suck and they can blow up your ecu. Instead use the multimiter trick by sticking a voltameter in the tps wire i think green with red stripe and adjust thescrew till the voltameter says 1 volt after that you are pretey much done ps i have only done this on and 87 so if you have that 89-91 **** with 2 tps adjustments i cant help you

 

How are the lights going to burn up your ECU?

 

Depending on the bulbs, they can draw too many amps through.

 

I am using LEDs which couldnt draw anything more then a few milliamps if thier lives depended on it. But I am gonna try the multimeter method. I guess its as close to 1VDC as you can get.

 

LEDS should not hurt ECU like J-Rat said.
But to answer the question...
this is what I found on some web-site
"For best results, adjust screw until both lights barely cease to light. Then tighten the screw 1/8 to 1/4 of a turn. Note: This screw is very sensitive to minute changes, so be precise! "

for me though, I adjust it so two lights are on, then turn so just one comes on and turn just a tad more. which is basically what is said above

 

From what I read...LEDs that are more than 12V will drain too much current from the ECU and fry it...so anything less than 12v is safe.

niner - thanks

 

I think that there is a a bit of confusion about the effect that a LED/LIGHT has on the ECU.

The voltage that is supplied by the ECU is limited to the supply voltage, that is 12 volts, attaching a LED/LIGHT does not increase the voltage suppplied, however the load that you attach to the terminals can draw current that may exceed the design of the ECU. That's when you can do the damage!

A LED will light with less than 2 volts applied, and in fact when connected to 12 volts a resister is need to limit the current flow to a level that will not burn out the LED or in the case of the ECU exceed the current draw that the ECU can supply. Voltage and Current are two different but interelated variables in an electrical circuit.

A standard LED with a 1000 ohm resister attached in series and connected to 12 volts will draw approximatly 11 mA which is well within the ECU's capabilites to supply.

As for adjusting the ECU by lights or volt meter that also seems to be a source of debate, the FSM says "lights" and many on these forums say "voltmeter". I'm nearly to the point after some throttle body work where I'm going to adjust my TPS and I will probably try both methods to see which works best.


P.S. If you want to make a set of test LED's that can be safely attached to the ecu for this purpose I can provide the details of my setup.

 

The FSM says lights so that's what I use. I've tried both methods and found they gave quite different results, i.e. set it by one method and it's out of spec by the other and vice versa. I got the smoothest on-off throttle transition (poor as opposed to complete crap!) with the lights.
As for setting via the lights, I've seen some sites that say screw it out until just after the first light comes on, and others that say screw it in until just after one light goes out. Completely opposite! With the age of these cars, they're all probably quite different, so I say play around until you find what works best for your car.

 

there is NO difference in adjustment performance with lights OR a voltmeter.

It doesnt matter wether you ise lights, (as long as they are safe) , an analog volt meter or a digital one.

It makes no difference.

If you perceive a difference, then your observing somthing ELSE, or your imagining it.

The TPS connector operates in ON or OFF state, "binary" if you will.

You cant get a finer adjustment from any one device or another.

I use LEDs or milliamp 12v bulbs.
(I have 2 checkers.)

Sniper_X

 

So when I had both the lights and the DMM hooked up at the same time and could not get both within spec, that was just my imagination? Well that's a load off my mind...

 

TPS USING THE LIGHT METHOD 101 BASIC: Start the car and warm it up. I mean get it hot as running temp, not luke warm. Connect the light assy to the green check connector. From now on I assume the one socket on the plug is up, and the other two below it. Now turn the engine off and just turn the key on. Do not run the engine or it ain't gonna work. Key to ON. Now turn the TPS screw all the way counterclockwise without unscrewing it completly. No lights will be on at this point. Now turn the screw clockwise until one light is lit. Now turn clockwise just a bit more until the second lite lights. That means you now have both lights lit. Now turn in an anticlockwise direction until you have but one light lit. Your done. ...........Now get your voltmeter and go to the TPS plug(not that damn green test connector) and put your positive lead in the back of the green wire with the red stripe. The negative lead to battery ground or any good ground nearby. Read the DC volts. It SHALL BE one (1) volt give or take a touch. Something like 1.05 or .95 volts. ..........Do use the lights and check your work by putting your voltmeter on the green/red wire. If it ain't 1 volt, go back and do it again. OR, just use the voltmeter and set the tps at one volt and go drink a coke or drink a beer. Now before someone starts reading their ideas into this, DO NOT DISCONNECT THE TPS PLUG WHEN CHECKING THE VOLTAGE AT THE GREEN/RED WIRE. EVERYTHING CONNECTED UP. Don't let a couple of lights wreck your day.

 

P.S The GOAL your are trying to reach is to have the tps set so that wiper on the tps pot (green wire with the red stripe) has an output to the ECU at pin 2G, of ONE VOLT (ok, .95v if you like). Keep your eye on the goal line. For verification of the GOAL, look at the FUEL AND EMISSIONS SECTION and the part in front of that section called CONTROL UNIT, where if has a table giving the output of each pin on the ECU. On pin 2G it says....................1v, engine warmed up.

 

In the FSM it covers using the lights, then checking the resistance between pins A and B of the TPS plug, not the voltage. At idle it supposed to be 1kÙ. Mine wasn't, it was ~1.3kÙ. Setting it right threw the lights out. I know it's probably because the TPS is knackered but the car drove nicer set with the lights so that's where it stayed. Matbe I'll check that voltage tonight ans see what I get.

 

I dont know what your were getting there, man, but im telling you, ther is either voltage at the terminals or there ISN'T.

Its ON or OFF.

One or the other.

I dont know what you mean by "in spec" but it you hook a VM and the lights together, then attach them to the connector, when you have a light, you have a reading on the VM of 12v. When there is no light, you will nothing or nearly nothing on the VM.

Thats about as exciting as it gets with the TPS.

Sniper_X

 

I wasn't talking about voltage at the diagnostic plug! Like I said above, I was checking resistance at the TPS connector (with a DMM) as per the FSM. With only one of the checker's lights on, the resistance should be 1.0k-ohm, mine was about 1.3 (out of spec). If I set it to exactly 1.0k-ohm I wouldn't have just one light on (out of spec). This is probably a stuffed TPS.