02 203 aux fan on all the time
hello- i'm grappling with an 02 c320 with the elec fan that's on all the time. sds says code p1999-signal wire to fan from me unit missing or broken. not true, it's in pin 39 in the ecm and i have continuity to the fan module. i have a warning message about low coolant-visit dealer and low washer fluid. ohmed out both sensors and they total about 320 ohms. couldn't find the exact spec in alldata, but have seen other posts that use that spec for 202s. i plugged in a new washer level sensor for grins and the message for low fluid goes away when i make sure the float drops from the body of the switch. upside down and the float flat, the message reappears. the sds says the sensor passes test when the float is down but fails with the float is up. could be a red herring. and yes. a new fan has been installed.
i'm waiting on a new coolant sensor to check specs, new against old.
i have no signal from the me to the fan module and the fan runs full blast. i'm ASSUMING the low coolant message is the reason. i can't find anything to verify the strategy. with the sds in live data the fan control is at 25%.
i can make the ac demand more fan and watch it rise on the sds. i can't activate the fan from the sds because it's on within 5-7 seconds of turning the key. all my live data is good and within range. no high temps, ac or engine. no high pressure on ac. a suprise that might be pertinent. while digging around for the problem, i found the engine coolant sensor had 1 green pin. sure enough, where it went to the me was green also. keep in mind, my engine temp was NOT of range. replace the sensor, clean the green out of the connectors and cross my fingers. still, all fan, all the time with no evidence the corrosion had gotten into the me controller.
any ideas? i've never had to wrestle with this before so i'm lost. any help would be appreciatted. thanks, chuck.
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