94 ATX Overheating Problem Need Help!!!

[gurucomputers]

Ok to start with I have replaced the thermostat, ETC Sensor, Water pump, and Radiator cap. I have a new radiator from a buddy that I am going to put in soon but here is the problem: I took the rad cap off and stuck a water thermometer about 10 inches down inside the rad. I started the car and let it idel for about 5 min. The inlet and outlet heater hose were the same temp to the feel. At about 10-15 min the water temp started to rise on the thermometer. The temp finally rose to 250 F and the fans did not come on. I looked at the guage on the in the instrument cluster and it was at the R on NORMAL. I know the factory guage is not accurate so I ignored it. I turned the A/C on and the Rad cooling fans kicked on. I watched the thermometer as it went down and the fans kicked off at about 200 F. Then the temp started to rise again with the A/C off. The temp got up to 250 and the fans did not kick on and water started boiling over. I turned the A/C back on again and the fans came on and the water stoped boiling over immediately. The temp went back down to about 200 F and the fans kicked off. What is the deal I am at a total loss for the problem.

 

[Ishodu]

ECT sensor could be bad. If you do a seach there are a few posts that will tell you were it is and how to replace it.

 

[gurucomputers]

ECT sensor could be bad. If you do a seach there are a few posts that will tell you were it is and how to replace it.

Ohh, I left that part out the ECT sensor was replaced as well. The one to the right of the T-Stat housing with the two wire plug.

 

[Ishodu]

How long ago and what kind? Brass or plastic?

 

[gurucomputers]

How long ago and what kind? Brass or plastic?

About 2 months ago and Im not sure about brass or plastic. I got it from Napa. Echlin Part # ECHTS4060.

 

[wood_e]

The napa part is plastic, get rid of that and get a brass one from autozone...

Wells SU201

 

[gurucomputers]

The napa part is plastic, get rid of that and get a brass one from autozone...

Wells SU201

Curious... This has been an on going problem. The Sho has been down for about 2.5 months. What difference does the brass one make over the plastic one. I will replace it for sure with a brass one but even if it is bad again you would think it would work at least one time. Could there be anything else that could be related to the problem???

 

[Sh03d]

I had the same exact problem. I flushed the system and it fixed it.

 

[Ishodu]

Unless you have air in the system. It appears that your fan relays are ok and the fan itself. So you computer is either not getting the signal to turn on the fan. (ECT) Or Its a wire issue and there is no signal getting to the relay from the computer.
The plastic ECTs have a bad rep for failing.

 

[gurucomputers]

Unless you have air in the system. It appears that your fan relays are ok and the fan itself. So you computer is either not getting the signal to turn on the fan. (ECT) Or Its a wire issue and there is no signal getting to the relay from the computer.
The plastic ECTs have a bad rep for failing.

Is there a way to check the signal from or too the ECT or the signal to the fan relays using a VOM. I was reading in the service manual that the CCRM controls the low/high fan control relays. Is that the box located on top the radiator on the drivers side with the large rectangular connector?

 

[Ishodu]

You could check the ristance on the ECT with a temp reading, There was a few charts posted in the last few months on the sensors output per degree in temp. The CCRM is located on top of the rad ya your looking at the correct box. There is also wiring diagrams in the "how do I" section on the main page of this forum.

 

[gurucomputers]

The fan functions properly by applying 12 volts directly to it. I grounded each of the two wires that control the relays to kick on the fans and they work fine when I manually ground them so the relays are good. I don't think the PCM is sending the ground signal to the CCRM for either low or hi cause the fans do not come on by themselves. All though the low side does only when I kick on the A/C. This would only leave the ECT being bad again or could there be a defect in the PCM. I would think if there was a defect in the PCM the car would not run at all and I get no check engine light or any codes.

 

[Ishodu]

Check the resistance in the ECT sensor.

 

[gurucomputers]

Check the resistance in the ECT sensor.

Problem solved. New bad ECT sensor to blame, Arrrrggggg NAPA Got brass one from Autozone and good to go fans work like new now. Thanks for all the help.