Hi,
The check engine light on my 93 190 e 2.3 is on. I decided to check the code on the little unit in the battery compartment. So with the key on (engine off) I pressed that little button for 4 secs & released it and waited...the red light does not blink at all. I tried for longer periods but no luck. The red light just does not come on. Any ideas ???? Please advise. Thanks

smk_texas
98 s420 - 53k
93 190e 2.3 149k

Hold it down for 2 secs... it should lite when held down, and then flash back when released..

Hello Arthur,

I tried it once again before this response. It does not light up when held down nor does it flash after I release the button. This is a California car and I also noticed that it has a custom alarm put in and the alarm red light is always on. I am wondering if there is short somewhere that is caused by this alarm. Thanks for the help.

smk_texas
98 s420
93 190e

Try holding the button with the reader tip of a pencil..
If it still does not light, you could have a blown fuse for circuit 15.

Thanks Arthur. I'll try that and post my findings.

I pressed the button down with a sharp pencil still no red light. All the fuses look fine. Circuit 15 says parking/tail light. It has a white fuse and it looks fine. Pls advise. Thanks

smk_texas

Also, I noticed that the o2 (yellow idiot light) light does not light up when I turn on the ignition (engine off). The other lights on the dash come on and go off after the engine is on but the check engine stays on. The o2 stays off all the time. Any ideas ???
Thanks

How many pins on that connector box?

8 pins.
Thanks

Ok
Somethin wrong with power feed to DM connector. Circuit 15 is not fuse 15 .
So............
Go here and build this simple tester.

http://members.aol.com/ajdalton7/ledtool.jpg
The only change is to use alligator clips for the Blk and Red bananna plugs .

I will then tell you how to access the xodes with the tool , including CE activation ones.

Thanks Arthur. I'll build it and let you as soon as I am ready.

Hi Arthur,
The tester is ready. I was surprised how cheap these parts were at RShack. Pls let me know what I need to do next. Thanks

Try this

Hook the red alligator to battery pos, blk to neg battery, and the test lead to the #3 pin on the DM connector box
Key ON . press button for 2/3 sec , release and see if codes come back.
What we are doing here is powering the tool direct with Battery 12v, as to eliminate any wire/fuse problems [ or sw/led ] the DM connector is having

I am assuming you have tested y6our new tool for correct led polarity???????????

Sorry Arthur, I think I blew ou my LED. I am on my way to RS to get another one. I'll be back. Thanks

You can not use a standard LED . You have to use one of the ones I gave the part# to b/c they have a built-in dropping resistor circuit so they can be used on a 12v system right off the shelf.
If you are using standard leds , you will blow them unless you ADD a dropping resistor.
That is why I specified a 12v LED Radio Shack part #...........
Also ,if you are not familair with Leds , they will not light if they are not hooked up according to polarity.. these are polarity sensitive... [ a diode passes current in one direction. so a light emitting diode is also still a diode and will not light if you wire it backwards]