How to read codes with LED on 95 140
 

I finally understood how to read/build the home-made check engine LED switch. Many thanks to JimF, Arthur Dalton, and others who posted. However, I am not able to get any reading from the LED switch. Here is what I did:

Connected pin 1 (-)
Connected pin 3 (+)
Connected pin 19
Turn on ignition
Push switch for 3 sec

The LED light would only turn on/off whenever I push the switch, there are no blinks. What did I do wrong?

The car is a 95 S320 with 38 pin diagnostic connector.

Jack

Picture of LED
 

Picture of the LED switch.

Jack

You are doing the steps correctly. Make sure the ignition is not in the ACCESSORY position, it must be in the RUN position. In other words, all dash caution lights should be on. Are you sure your test pins are making good contact with the 38 pin connector? Are you sure you built the tester correctly?

The connections are;
"J1" = Pin 3 --> +12V
"J3" = Pin 1 --> Gnd
"J2" = Pin 19 --> Diag Module connection.

Is the ignition swtich set to "position 2"??

Try 'pushing' the sw for 5 - 6 secs

Thank you for the replies. I think the test pin have made contact, it is the same pin I used for the ground and 12v. Is there a spec for the wire thickness. I used some lite ga wires from computer (wires from CD player to sound card).

I tried it again:
Key turn to number 2 position (all dash lights are on)
Press the switch for 6 sec
Test LED would turn on and off as I press the switch

It acted that I am getting power to the test LED, but did not cycle to turn the LED to blink.

Jack

20 gauge solid copper seems to be about the right size. It is available as bare wire in any hardware store - often sold as picture hanging wire, maybe 2 or 3 bucks.

The reason I asked about the connections was to have you verify that they are correct.
So far, we 'know' that the J1 to J3 paths is good since when you push the RS 'momentary' switch the LED lights.

Now try this test: With the connections in place, take the "J2" end and touch it to GND; the LED should light. I have a feeling it won't??? If not, do some t/s to see what's wrong; 'fuse'???

It worked
 

Thank you for everyone's replies. I rebuilt the LED kit with 18GA themostate wires.

The problem was I did not know how it works, how to pess the light. This time, I hold the switch a little longer. I got 5 or 6 blinks (I am not sure), because on my third try, I only got one blinks. I will have to wait for the CE light to return.

Based on JimF's fault table:
5 blinks is EGR inoperative (bad valve or plug tube)
6 blinks is idle speed control inoperative. I don't know what it mean, the car have little over 100k miles. It run perfect, the idle is good.

Jack

Glad you got it going: not sure what the "wire" had to do with it but it works.

The "DTC" that could dent your new year is the "ISC Faulty", #6. If you want to see what MAY (probably) happen, read MENU#24 about the saga of my "ISC faulty" DTC. That's how the infamous ETA failure starts. Or the other corollary, equally as bad, is a bad wiring harness.

Right now, just reset all of the codes and see what happens. The reset procedure is in MENU#2 in "Erasing DTC Memory".