Check Engine Light / MAP Sensor Unplugged
 

1999 Ram 3500 Cummins 5.9L
Today I installed a Dual Map Sensor for my HHO system. I unplugged the MAP sensor while the engine was OFF, but the ignition was ON, to move the wires. (I know, should have had the ignition off, but I was listening to XM) Check engine light came on. I plugged the MAP sensor in and tried to reset the CEL with ScanGaugeII. The Gauge cleared the CEL, but it immediately came back on. I also tried to disconnect the battery for 10 min, but that doesn't clear the CEL either. The engine barely runs and has very little power. (Limp Mode?) Will the CEL take some time to reset? (The code is for low MAP voltage) Help! Any suggestions? Did I mess up the MAP?

IIRC, you are going to have to have the batteries off for around a little over an hour. If you have everything hooked up correctly now that may work. If the CEL comes on after that, but the truck runs normal try making a few trips with it. If everything is right after so many starts the computer should shut off the light and you will be on your merry way.

Left the batteries disconnected for 2 hours and nothing changed. My ScanGaugeII resets the CEL for a second, with the engine OFF but the ignition ON, but the CEL comes right back on. When driving it lacks power and acceleration...a big difference from when it was running fine. I even bought a regular scan tool to clear the codes but it doesn't work, either. I hope I didn't do something to the MAP sensor or CPU. Any other suggestions?

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Wow, got this one figured out. When I removed the plug to the MAP sensor to check the voltages I inserted the probe of my voltmeter into each connector. There is a mechanism inside each female connector (in the plug) that opens up the connector, kind of like a flower, to accept the male plug when you plug the connector back into the MAP sensor. Apparently one of these devices stuck in the open position and the female connector couldn't grip onto the male pin when I plugged it back in. I guess we learn something every day.

thanks for the followup this was puzzling