Simple Injector Signal Tester

I made this very simple tester so that I could determine if my condenser fan and oil cooler fan was in either low or high speed mode in my car while I was driving. Actually, it can be used for just about any test.

Having just read this month's Bench Wrenching article "Troubleshooting - The Art of Critical Thinking, Paul wasn't easily able to check if there was a signal going to the injectors.

Well I just happened to check the injectors on a local's Porsche 911 the other week. The owner installed an Electromotive TecGT engine control system and it wasn't running right; injector #5 wasn't getting a signal at all and injector #3 was intermittent. The problem...the AMPSEAL connector...brand new and faulty right off the bat. The LED's flashed nicely on all other cylinders. And this simple tester avoided having to drag my oscilloscope over to his place.

Anyway, this or better yet, a version of it, can be stashed away in your took kit. A simple LED, resistor, some short leads and two pins can be put into a 1"x 2" zip lock bag. The pins are used to slide down the injector connector to make contact with them. My unit has banana jack receptacles so that I can use my test leads with it.

A bright LED should be chosen along with an appropriate series resistor.

Radio Shack and other electrical supply places sell 12v LEDs with proper resistance built in. I used them for a tester I made to test Hall Effect Sensors (HES). Voni carries a 12v LED tester in her tool kit now.

But the episode described in that Benchwrenching column happened at a time, and at a location that I had neither of these devices at my immediate disposal.

PGlaves said:

Radio Shack and other electrical supply places sell 12v LEDs with proper resistance built in.

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Even easier! I made mine from stock I had in my shop. I'll get one of those ready-made LEDs for the one I'll keep in my toolkit.

PGlaves said:

But the episode described in that Benchwrenching column happened at a time, and at a location that I had neither of these devices at my immediate disposal.

Click to expand...

Well that'll learn ya. I'll be putting one in my toolkit.

Schematics ???

ka5ysy said:

Schematics ???

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A simple LED in series with a resistor; in my case, a 2K ohm resistor for the LEDs that I had.

Or you can go Paul's route and get the all-in-one-package 12V LEDs. That is easier.