Mechanics

LOW SPEED FANS WILL NOT COME ON AT 2

1997 Chrysler Concorde

Engine Cooling problem
1997 Chrysler Concorde 6 cyl Two Wheel Drive Automatic 145000 miles

97 Concorde 3.5L, the low speed cooling fans will not come on at 219 degrees. The high speed fans will come on at 230 degrees and go off at 219. I have tried 3 different ECMs and I experience the same problem. I have spoken with the manufacture of the ECMs and they suggested checking voltage drops, this was done and 0.015v was the reading from all grounds and wiring from the ECM to grounds, from ECM to both low and high speed realys. With a scanner connected I can activate both the low speed and high speed relays therefore making the correct fan work. With the engine running and scanner connected I get the following voltage information from the ECT to the ECM: 1.96v=219 degrees NO Low Speed fan operation. 1.76v=230 degrees High Speed fan comes on, then goes off at 1.96v. In addition, I have a 1997 Chrysler LHS with a similiar problem, at 230 degrees it will switch on the low speed fans and not the high speed fans. If I switch these ECMs the problem goes with the ECM.
Avatar
Rneathery11
December 10, 2009.




Have you check the coolant temp sensor? Have you checked the low speed cooling fan in the power distribution center? Also check fuse D (40amp) in the power distribution center this sends power to the low speed relay. Once you find the low speed relay check for power at the tan wire coming from the low speed relay to the low speed motor.

Racefan966
Dec 11, 2009.
The ECT was replaced because the original was defective ohmn checked it was way of of range, Low Speed fan is not receiving a ground signal from the ECM. The Power from Fuse " D" is going to the relay and the power from fuse " 20" (inside fuse panel) is going to the ignition side of the relay. If I supply a ground the low speed fan relay the fan will come on and stay on until I shut off the engine and set a low fan relay code.

Tiny
Rneathery11
Dec 11, 2009.
Ok that wasn't mentioned before. Now here is how it is wired. So the fans are grounded together at the left front frame rail. Now there is a power control module on the right fender side sheild that is the relay control module for the fans. It has a white wire and a dk blue wire with a pink stripe this is what closes the relays or controls the grounding.

Racefan966
Dec 11, 2009.
I presume what you are calling the power control module is the Engine Control Module? The ECM is located on the right inner frame rail and the grounds for the ECM are located in this area, all grounds from the ECM have a voltage drop of 0.015v during operation. The white wire coming out of the ECM is suppose to engerize a ground to the low speed relay when the ECT reads 219 degrees and dengerize when the sensor reads 199 degrees (according to information from AllData). Problem I am having is the low speed fans DO NOT come on at 219 degrees. I have to wait until the coolant reaches 230 degrees and the high speed fans will come on and shut off at 219 degrees.

Tiny
Rneathery11
Dec 11, 2009.
I know you might be busy, but please help.
Thanks

Tiny
Rneathery11
Dec 11, 2009.
Is the CTS an OEM part-check its resistances Hot/Cold readings

The PCM powers the coil side of the relay on the white for the low side relay-the black wire is for both fan motor terminated at left front frame rail


http://www.2carpros.com/forum/automotive_pictures/12900_relay_26.jpg


Tiny
Rasmataz
Dec 11, 2009.
Is the CTS an OEM part-check its resistances Hot/Cold readings

The PCM powers the coil side of the relay on the white for the low side relay-the black wire is for both fan motor terminated at left front frame rail

What do you mean by CTS? I presume this is the Engine Coolant Temperature SAensor (ECT). The original was ohmn checked and was out of range both cold and with 219 degree coolant. (AllData specs).
I believe you have it backwards, the power to one side of the low speed coil is supplied by the fuse inside the junction block under the hood. The ECM supplies a ground to the other side of the coil, therefore closing the circuit for the low speed fans to operate. The low speed fans should come on at 219 degrees and go off at 199 degrees. The ground wires for both of the cooling fans do terminate at the left front rail. A voltage drop of 0.015v is recorded when the High Speed fan engages at 230 degrees (measured from the high speed relay to the fan ground) Voltage drop measured at the low speed circuits shows battery voltage at all times. It is my opinion the ECM is not suppling a ground when the ECT reaches 219 degrees.

Tiny
Rneathery11
Dec 11, 2009.
My bad I'm partially blind-I'm think of the same thing here ( It is my opinion the ECM is not suppling a ground when the ECT reaches 219 degrees ) but 3 different PCM and still doing the same old thing

Tiny
Rasmataz
Dec 11, 2009.
No problem, I wear bifocals and it is hard to follow wiring at times.
I know it is hard to believe that 3 remaned ECMs still give me the same problem. I am argueing with the manufacture about this also. What I am tring to seek is if anyone has experienced this problem and what was the solution to the problem.

NOW let me throw in a curve ball.

I also have a 1997 Chrysler LHS with a similiar problem. The low speed cooling fan come on at 230 and will not shut off. The high speed fans never come on unless the A/C is on and the High PSI side will activate them for about 20 seconds and then the high speed fans will shut off.

NOW THE CURVE BALL: I can switch the ECMs from the LHS to the Concorde and vise-versa. The problem GOES WITH THE ECM.
I cannot get the manufacture to understand this problem.

Tiny
Rneathery11
Dec 11, 2009.
I am with you it sounds like the ECM is the problem. Have you used a jumper and gounded the ECM to see if anything changes?
AD

Racefan966
Dec 12, 2009.

AD