Hello all! What a great forum! I was hoping someone could help with a brain box issue I have, my 92 SPFI Loyale popped a resistor on the ECU's PCB. It's resistor No.1. What I need is the specs on the replacment resistor. . . A brain box out of a 1990 is getting me by for now, but I would like to simply re-solder a new resistor into place, seeing as the rest of the ECU bears no signs of further damage (we hope, right). Most people are looking at me kinda funny when I ask for this, everyone keeps telling me to go to the junkyard for a used ECU, but I'm feeling stubborn and the soldering wand is ready. I was simply testing my MAF for resistance and I managed to screw something up. . "POP". While we are at it, does anyone have the lowdown on general compatibility between brain boxes for SPFI's? In case I end up in the junk yard after all . . .

I WISH I had the schematic for a brain box. But here is something that might get you by. It is a color code calculator. just put in the colored bands on the resistor in the calculator and it will spit out a resistance value and tolerance. Go to radio shack and hope that they have that resistor. If they don't

resistors add in series ie. R1+R2+R3=Rtotal

resistors divide in parallel ie. (1/R1)+(1/R2)+(1/R3)=(1/Rtotal)

Good luck.

Is it a normal size resistor with the color bands or one of those tiny square surface mount resistors? Do you still have the old resistor? If so, you can reuse it. If you still have the old resistor and want to replace it, just get one with the same color bands if it is a normal resistor. If you lost the resistor, you can pull an identical ecu from a junked car to see what kind of resistor that goes there. If you do that, then you might as well just buy the ecu unless the salvage yard wants lots of money for it.

Well the particular resistor is scorched to the point were it is indecipherable. Guess I'll try the salvage yard. Anyone else looking for some select components? The yard I pick from has about a dozen GLs,DL,XTs,Loyales, just about very model and variant you can think of. The RXs diffys have already been stripped though. . . Thanks for the info guys.

I don't know how you could have damaged that resistor while checking the resistance of the MAF sensor unless you had power connected to the ECU somehow. I assume you know that power must be removed to the circuit when you are trying to measure the resistance of it. Removing the negative battery connection is a good procedure to do when doing something like this. You should also isolate the component you are trying measure from the circuit to avoid measuring errors. If you were trying to measure the MAF sensor resistance the MAF should be disconnected at the connector to it before measuring it, with the power off before disconnecting it. When other things are tied to the area of concern you can get false resistance measurments due to the other paths the circuit or component is tied to.

 

Unfortunately, there may be more damaged components in the circuit besides the resistor depending how the circuit is designed and the excessive current traveled through it.