240 90 240 Crank Position Sensor - OBD Not flashing 200

OK-Yesterday I was driving home from an appointment, and the car just died. I did a quick check, no fuel pump (fuel pump relay not clicking during cranking-jumpered the fuel pump fuse and got the pumps running) and no spark (explains fuel pump relay not activating).

I figured it was the CPS since it's original (195K on the car). Also, I assume the car will start after it sat for a while if it was the CPS.

Towed the car home (only 5 blocks away from home).

So, as I waited for the car to cool down, I checked the OBD system. Both in pin #2 (fuel) and #6 (ignition). The LED lit up when I pushed the test button, but the system didn't give back any code flashes. I assume it was because the pins were dirty or corroded. Cleaned everything, still no code flashes.


I figured it was either a OBD box or something to do with the CPS.

I unplugged the CPS plug on the firewall and checked the resistance of the three pins. I got about 200 ohms between two pins (didn't bother to figure out which pins) and nothing between the other pins. The resistance between the two pins that gave a value would only read a value for a few seconds, than nothing. Have a new CPS ordered and will replace as soon as possible.

Well, after a couple of hours sitting, the car started right up. I checked the codes again, and the OBD system gave me codes for both ignition and fuel systems. Ignition gave me 1-1-1 - no faults detected, and fuel gave me 1-2-1 - faulty AMM (which I replaced and the code went to 1-1-1).

Question: Has anybody else seen no codes flashing in the OBD system when the CPS is going/went bad? Or is this a something else (like a sign of a bad ECU)?


BTW-the car is a California emission car. Original ECU has been changed out with a non-problematic ECU.

Paul

malloy1 said:

So, as I waited for the car to cool down, I checked the OBD system. Both in pin #2 (fuel) and #6 (ignition). The LED lit up when I pushed the test button, but the system didn't give back any code flashes. I assume it was because the pins were dirty or corroded. Cleaned everything, still no code flashes.

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I think the issue of the OBD diags not working is separate from the CPS/car dying.

The OBD diag box has two wires to power and ground, plus one wire to the EZK (#6) and one wire to the ECU (#2). The switch on the box shorts the little probe wire to ground. The LED is also connected to the probe wire and turns on when the probe wire is grounded. When the little OBD probe is inserted in #2 or #6, it connects to either ECU or EZK, but not both at once. Either pushing the switch, or the ECU/EZK (whichever is connected) can ground the diag wire and turn on the LED.

OK so far? Try unplugging the little probe wire and pushing the button - LED should turn on and off. You can also connect a multimeter to the probe wire -- should be ~11volts normally and 0volts when button is pressed. Try tapping the probe wire to ground and LED should also turn on and off.

With this setup, it is unlikely that both your ECU and your EZK stopped responding at the same time. I'd check the diag box connections again, and make sure that the plastic housing hasn't broken allowing the #2 and #6 pins to shift too far down.

Check for and oxidized fuse/fuse holder by the battery.

Better yet replace that plastic and corroded fuse holder with a waterproof fuse holder you can buy it from radio shack

I think we have the same problem with our OBD readers. Mine also only displays codes with the engine running. I haven't looked into it too much, tbh, but I'll be following this for more ideas.

ZVOLV said:

Check for and oxidized fuse/fuse holder by the battery.

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If neither ECU produces code, but the OBD LED lights when you push the test button, I believe this is the answer ^^.

I've never tried using the OBD box without the constant battery power to the ICU and ECU before this morning. That's exactly how it behaves. Pull the 25A fuse to verify the behavior.

Yup-Pulled the fuse and was the same symptom:

-No fuel pump relay activating
-No spark
-OBD LED lights up when test button is pushed, but no code flashing in either the #2 or #6 pin.

I did clean the fuse and sprayed the holder and fuse with deoxit when I was cleaning the OBD box. I forgot to mention that. The car didn't run after I cleaned the OBD box and fuse holder. The fuse and holder was corroded. I'll replace the fuse and holder too.

Paul