so i replaced my thermostat the other day now i got a check engine light on..replaced my temp sensor and also my sensor plug still getting a check engine light. the thermostat i installed is a 195 temp. any ideas?
I'll bet you still have an air pocket in the cooling system. I had this problem with my 86 Caprice wagon. It typically took about a week of driving to get the air out of the cooling system. Until that time, I would periodically get a check engine light and temp sensor code. I'm guessing the code was due to the fact that there was a steam pocket around the sensor that gave it a spurious reading temporarily.
ok so the motor has an edelbrock intake on it.. the sensor is threaded into the intake. i removed it from the thermostat housing. the thermostat is opening. the car has electric fans on it and i have tried turning them off. i used an ohm meter at the ecm and checked the circuit i have 5 volts at the sensor and continuity through out the circuit.. could my ecm have died? as in i have volts and the proper ohms of resistance but the computer cant see any of it..
You need to plug it in and turn the car on...one wire has the 5V in, and the other should have something like 3.5 to 4V. Then, start the car and watch the voltage on the second wire; it should go down as the engine warms up, to about .8-1V or so (feel free to correct me if I'm off), but that's how it should work. And checking continuity on the harness with the computer connected gives you way incorrect readings. Disconnect the ECT sensor plug and the corresponding computer plug for those wires, jumper the ECT plug with a paper clip and put your ohmmeter leads on the two wires at the computer end; you should have 1 or less ohms. Any higher means you have a damaged or broken wire.
OK what I did was unplug the harness from the ecm. I checked from the yellow wire to the dark greyish two leads over and that is where I found continuity. I don't know if I had the meter on the right ohm setting but the numbers I had gotten is 2.02 from lead to lead at the ecm then I checked at the sensor itself and got a reading of 2.01 ohms.. Plugged into the ecm at the sensor I had 5 volts. Nothing on the grayish blackish terminal.
So I have been searching a lot of sites and have come up with a lot of people saying ecm failure on the temperature circuit only either reading real high over 300 degrees or crazy cold -27 degrees or more. Has this ever happened to anyone else?
ok well everybody thank you all very much for the help and input. so i had no shorts the the coolant temperature sensor circuit but the ground side of the circuit was dead. i tested the car with a second computer that was removed from my brothers car a couple of years ago. everything was good for about an hour of driving then that computer died in a different way got a tps code. then a coolant code then a o2 code... i thought i looked at every inch of wiring but i did miss something under the tape where the air pump diverter valve wiring was taped up the insulation was destroyed.. i started to untape everything and follow the loom up the fender well and found more bad spots. the wiring was rotting out in many spaces. so i am no longer computer controlled.. i installed a edelbrock carb and an h.e.i. vacuum advance distributor, with a b&m adjustable torque converter controller. i am sure i have let so of the purists down. i felt i was going to end up just fighting a losing battle continuing on the path i was on. i fought with the e4me ccc carb since i installed the 400 engine in the 305's place. i however did not cut or remove the wiring harness. it is tucked in the fender. i talked to my inspector before i did the job and his answer was what to you so long to relise i was fighting a losing battle since i could not get a new prom flashed to match the 400's ignition curve in the first place. so im sorry to the purist out there i did really fight to keep it as close to original as possible but the system died.
Well, then your "tech inspector" is clueless. People have burned new PROMs for the CCC system for decades. You can find BIN files online to do it yourself. There have been folks who have burned PROMs to support an Olds 403 in place of the 307 in the 1980s cars with no problems.
just a little update that doesnt really matter bailed out on the edelbrock carb rebuilt my old holley 4011 bought it about 20+ years ago, so much easier to tune, and about a 14% gain in mpg. also out of lazyness i reinstalled the ecu.. seems the a/c needs it to work. also got back cruise control.
Well, alright. That 4011 is a very easy carb to deal with, and it gets the better mileage because it's a spreadbore (smaller primaries vs. secondaries).
