QuestionQUESTION: I have a 96 deville with northstar. Ive been trying to figure out this code p1660(cooling fan control circuits) I think i narrowed it down to the problem. I did all the test u told me like the ground test on the relays while ignition on or all times etc (u sent me a list of what to do) well everything was ok but the ECS fuse. I check it for power with ignition on like u told me. one side of the connector where u put fuse in has power but not the other so im thinking its an open circuit. how do i repair this. been dealing with this code for too long and im hoping this is it.
ANSWER: The ECS fuse ONLY has battery voltage on BOTH sides when the engine is running.
Are you using a VOLT metr to make sure you are getting battery voltage ?.
E-mail me at: onlineautohelp@msn.com for additional electrical schematics.
---------- FOLLOW-UP ----------
QUESTION: yes i am using a voltmeter and thnx u were right it does have voltage on both sides when engine running. I did all the test u told me to do in the past like checking for voltage at all times via the red wires on relays 1 and 3 oh btw this is about the 96 deville northstar. i changed pcm,did the ground test for high and low speed changed ect sensor ect. Im just wondering about 2 things. 1. when u told me to unplug the ect sensor to see what it does what am i looking for? i unplugged it and nothing happened. 2.does not having my ac compressor filled and running have anything to do with it. compressor works fine its just shut down cuzz theres no freon in it and the 2 lines that go into the compressor is disconnected. I just wanna get rid of this p1660 code so my fans can turn on high when there supposed to.
Answer When you unplug the ECT sensor the fans should both go to high speed, Do they ?.
What your problem IS, Is that your AC relay is not providing battery voltage to fan relays #1 and # 3.
Try this:
1. unplug the AC compressor relay and jumper circuit D3 (orange wire) to circuit C1 (dark green wire) with a jumper wire. Leave AC relay unplugged.
2. Unplug the 2 wire AC compressor plug and leave it unplugged.
3. Start engine and see if you you have low blower on both fans when the engine warms up.
4. If you do, Wait until the engine gets hotter and see if the fans turn ON to high speed. If you cannot get them to turn ON to high speed. Block off the radiator with a piece of cardboard and being careful not to overheat the engine via watching the engine temp and overtemp light the fans should turn ON to high speed as the engine gets hotter.
Let me know.
If this does NOT work, I can give you my FAX # and we can talk via my fax line and I can guide you thru the above procedure.
