power transistor

[big monkey racing]

does anyone know wat problems a bad power transistor would cause.

[Hijacker]

It would cause a no-fire situation. It's a link between the ECU and the coil, so if it were to go bad, the ECU can't cause the coil to fire. Look on page EC-161 of the service manual for how to test the PTU (assuming this is for a KA)

[big monkey racing]

what I ment to ask is what are the symptoms of a breaking down power transistor

[Rucca]

Misfiring - car dying randomly. Intermittent no starts... something like that. Just imagine what would happen if you weren't getting spark or sometimes weren't getting spark.

[babysirt]

I have been having intermittent no starts so I tested the coil and resistor. They are fine. So I figured it was the power transistor.

Page 161 in the EF&EC section of the manual says that if it read infinity or zero with the positive lead on B and the negative lead on A, then the transistor is bad. I tested my transistor and the resistance between terminal A and B was infinity even when I swapped the polarity. So according to the manual, it is bad.

I went to the junkyard and pulled one of another 240SX and one of a Nissan Maxima. I tested them and they both tested the same way. Was i just really lucky and found two other bad transistors or is the manual wrong? And can I use a power transistor off any Nissan?

[Rucca]

Your multimeter is probably just not very good. I believe the resistance value is in the Megaohms, i.e. millions of ohms. Many lower quality meters will see that as infinite.

[babysirt]

You are right. It looks like the resistance is over 2 megaohms... My cheap RadioShack multimeter wasn't showing any resistance on the smaller scales.