msmithmmx Posted August 4, 2007 Author Share Posted August 4, 2007 Cougar, Is there any relays inside the car that can be tested. I also found out that only the highest setting on the AC/heater controle will turn the inside fans on. The first 3 setting do nothing. I switched the whole AC/Heater controls out, no change. I am about to just sell this 97 OBW AS IS. Link to comment Share on other sites More sharing options...
Cougar Posted August 4, 2007 Share Posted August 4, 2007 I don't think there are any more relays that need to be checked. You already proved the fans work. It would really help if you compared the resistances of the sensors on both cars and let me know what they are. You might also just try shorting the sensor leads that go to the sensor on the problem car to see if the fans will turn on then. I think as the engine gets hotter the resistance of the sensor goes lower. Link to comment Share on other sites More sharing options...
OB99W Posted August 5, 2007 Share Posted August 5, 2007 [...]I also found out that only the highest setting on the AC/heater controle will turn the inside fans on. The first 3 setting do nothing. I switched the whole AC/Heater controls out, no change. I am about to just sell this 97 OBW AS IS.It's very likely that the blower motor resistor has an open circuit. That multi-section resistor is used to slow the blower motor when the lower speeds are selected, but is out of the circuit for the highest speed (full voltage is applied to the motor). The fact that the blower works at the highest speed verifies that the blower relay and motor are okay. Sometimes the resistor opens from normal use, sometimes due to the blower motor drawing excessive current. You could try swapping the resistor, but should verify that the one you're swapping in is okay. Of course, this problem is separate from the one with the radiator fans. What Cougar suggested should help with that diagnosis. Link to comment Share on other sites More sharing options...
msmithmmx Posted August 5, 2007 Author Share Posted August 5, 2007 1) Where is this resistor? 2) I did confirm again when I pull just the connector off the Coolant temp sensor the fans inside the engine compartment turn right on. This is with everything else connected. Link to comment Share on other sites More sharing options...
OB99W Posted August 5, 2007 Share Posted August 5, 2007 1) Where is this resistor?See these:http://www.ultimatesubaru.org/forum/showthread.php?t=63197 http://www.ultimatesubaru.org/forum/showthread.php?t=69923 http://www.ultimatesubaru.org/forum/showthread.php?t=53396 2) I did confirm again when I pull just the connector off the Coolant temp sensor the fans inside the engine compartment turn right on. This is with everything else connected.Perhaps you've found the problem; why not compare the resistance of the sensor with a known-good one? EDIT: Of course, the sensors should be at the same temperature when comparing them. Link to comment Share on other sites More sharing options...
Cougar Posted August 5, 2007 Share Posted August 5, 2007 I think the cooling fan may have two speeds but I don't think there is a resistor in the circuit to do that. I think they have a split coil winding in the fan motor itself for that. It is good to hear that the fan turns on when you remove the sensor connection. I remember a comment from another board member in the past about that happening and was going to mention it here. Since the fan works that way it would appear that the sensor is the problem. I thought that the sensor resistance would go lower as the engine warmed up but it looks like it is the other way. Did you ever measure the sensor resistance? Link to comment Share on other sites More sharing options...
msmithmmx Posted August 5, 2007 Author Share Posted August 5, 2007 Good Lord 1) Regarding my inside fans only working at the highest level. I pulled out the resistor, its all rusted and I see where there is a broken connection inside. How much does it cost. Question, Is there a way this is causing my problem with the fans inside the engine compartment? 2) I unplugged the Coolant temp sensor. And with just the key in the ACC postion and the AC turned on I am getting .002 at the wire. 3) I have a new sensor from NAPA. without plugging the new one into the coolant pipe and just plugging into the harness I am getting the same results. Do I actually need to put it into the pipe. 4) How do I test resistance with it plugged into the coolant pipe. You guys rock.... And a pic of the little nasty bugger included Link to comment Share on other sites More sharing options...
OB99W Posted August 5, 2007 Share Posted August 5, 2007 Good Lord1) Regarding my inside fans only working at the highest level. I pulled out the resistor, its all rusted and I see where there is a broken connection inside. How much does it cost. Question, Is there a way this is causing my problem with the fans inside the engine compartment? I don't know the cost of the resistor, offhand. This problem is unrelated to the radiator fans not coming on. Have you tried using the green (test) connectors located under the dash? Reconnect the coolant sensor, plug the two green under-dash connectors together, and then turn the ignition switch to ON (don't start the engine). Do the fans cycle? Link to comment Share on other sites More sharing options...
Cougar Posted August 5, 2007 Share Posted August 5, 2007 To check the resistance of the sensor all you have to do is place the meter probes across the wire contacts of the sensor. Never measure resistance with the power on to the device being tested. It is best to isolate (disconnect) the device from the rest of the circuit also so other devices in the circuit won't affect the reading. What we really need to know is what the resistance of the sensors are when they are around 205 degrees F. They should be close to the same value. I don't know what the values should be unfortunately. If you want to test the new sensor without installing it you could place it in a shallow pan of near boiling water. Keep the contacts dry if you do this. OB99W has a good idea to test the fans. This will test the ECU control side of the circuit at least for both fans. Since the main fan works ok by pulling the sensor connection I think it will also work ok if you do that procedure. Link to comment Share on other sites More sharing options...
msmithmmx Posted August 5, 2007 Author Share Posted August 5, 2007 I don't know the cost of the resistor, offhand. This problem is unrelated to the radiator fans not coming on. Have you tried using the green (test) connectors located under the dash? Reconnect the coolant sensor, plug the two green under-dash connectors together, and then turn the ignition switch to ON (don't start the engine). Do the fans cycle? I connected the the 2 green connectors and when I trurn the key to ACC. I hear the engine fans cycle on and spin low to to high and then repeat. Link to comment Share on other sites More sharing options...
msmithmmx Posted August 5, 2007 Author Share Posted August 5, 2007 We fixed one issue, I replaced the fan resistor, I the AC/Heater fan now works on all speeds. The fan in the engine compartment still does not come on when I turn the AC on. I even put the new sensor in boiling water. Link to comment Share on other sites More sharing options...
Cougar Posted August 6, 2007 Share Posted August 6, 2007 Does the car only have one cooling fan? I was thinking there was two in it. I will be home on Wednesday where I can check my service data. Something is still missing here I guess since the fan doesn't turn on when the sensor is hot. It is good that the fan turned on in the diagnostic mode. I thought it might. I appears to me that something is still wrong with sensor side of the ECU circuit that is causing a problem. Link to comment Share on other sites More sharing options...
OB99W Posted August 6, 2007 Share Posted August 6, 2007 [...]Something is still missing here I guess since the fan doesn't turn on when the sensor is hot. It is good that the fan turned on in the diagnostic mode. I thought it might. I appears to me that something is still wrong with sensor side of the ECU circuit that is causing a problem.It's "interesting" that the fans come on if the sensor is disconnected, but not when it's hot (possible fail-safe operation?). Since it appears that the fans cycled correctly under test, the ECU output switching would appear to be normal; I agree that the problem seems to be related to an ECU input/sensor. I seemed to remember that there's some usage of VSS (Vehicle Speed Sensor) data to determine fan operation, and the following appears to verify that: http://endwrench.com/images/pdfs/CoolingInfo.pdf Msmithmmx, besides what we've been discussing -- 1) Are there any other issues with the way the car is operating? 2) Has the "Check Engine" light come on at all during operation? 3) Does the CEL light when you turn the ignition switch ON, before starting the engine? 4) Did the CEL flash (about 3 times per second) when the green test connectors were plugged together? Link to comment Share on other sites More sharing options...
msmithmmx Posted August 6, 2007 Author Share Posted August 6, 2007 Look at #2 when the car was delivered it had a check engine light for a speed sensor. I erased it but since then it was only moved a few feet into the garage. 1) Are there any other issues with the way the car is operating? When I purchased the car a week ago the guy told me it had a busted HG. I thought I would fix the fan issue first. 2) Has the "Check Engine" light come on at all during operation? Real funny you mention this, when the car came it had a check engine light with note a speed sensor malfunction. I did not mention this because I never even thought it could be an issue 3) Does the CEL light when you turn the ignition switch ON, before starting the engine? Yes the light does go solid 4) Did the CEL flash (about 3 times per second) when the green test connectors were plugged together? Yes, 3-4 times Link to comment Share on other sites More sharing options...
OB99W Posted August 6, 2007 Share Posted August 6, 2007 Look at #2 when the car was delivered it had a check engine light for a speed sensor. I erased it but since then it was only moved a few feet into the garage.[...] 2) Has the "Check Engine" light come on at all during operation? Real funny you mention this, when the car came it had a check engine light with note a speed sensor malfunction. I did not mention this because I never even thought it could be an issue [...] I'd suggest that you find and correct the VSS problem. If you have it, the exact DTC (diagnostic trouble code) would be useful. I can't say for sure that resolving the VSS issue will take care of the radiator fan problem, but they can be related. Besides, VSS problems can force the ECU into a "limp" mode, causing overall performance to degrade. As a general rule, anyone asking for help on the forum should always reveal any CEL indications and the DTCs behind them. It won't always help with the diagnosis, but it certainly won't hurt, and might just be a major clue. Link to comment Share on other sites More sharing options...
Cougar Posted August 6, 2007 Share Posted August 6, 2007 2) I unplugged the Coolant temp sensor. And with just the key in the ACC postion and the AC turned on I am getting .002 at the wire. This statement is a little confusing to me. I wanted to ask you what wire are you talking about here and, is that a voltage reading you are giving there? If this is a voltage reading of the coolant sensor wire while the sensor is connected this isn't good. Link to comment Share on other sites More sharing options...
msmithmmx Posted August 6, 2007 Author Share Posted August 6, 2007 This statement is a little confusing to me. I wanted to ask you what wire are you talking about here and, is that a voltage reading you are giving there? If this is a voltage reading of the coolant sensor wire while the sensor is connected this isn't good. .002 was the voltage reading at the tip of coolant sensor wire with it disconnected and the key turned to ACC Link to comment Share on other sites More sharing options...
msmithmmx Posted August 6, 2007 Author Share Posted August 6, 2007 I unplugged the speed sensor on the transmission, anything I should look for? Link to comment Share on other sites More sharing options...
Cougar Posted August 6, 2007 Share Posted August 6, 2007 .002 was the voltage reading at the tip of coolant sensor wire with it disconnected and the key turned to ACC There should have been a voltage on that lead. After I reread your reply I realized you said the key was in the ACC position. I think the key will need to be in the RUN position, though the engine doesn't need to be running, to measure the voltage on the lead. The ACC position only turns on certain accessories. Another thing is you may be on the wrong sensor. I think the coolant temp sensor for the ECU has two wires going to the sensor. I may be thinking of a different model though. I guess one way of finding out if this is the correct sensor wire is to check the temperature gauge. If it changes when you disconnect it from the sensor then it is the wrong one. This may explain the trouble we have been having with it. Link to comment Share on other sites More sharing options...
msmithmmx Posted August 7, 2007 Author Share Posted August 7, 2007 I am on the coolant temp sensor, 2 wires Link to comment Share on other sites More sharing options...
OB99W Posted August 7, 2007 Share Posted August 7, 2007 I unplugged the speed sensor on the transmission, anything I should look for?That probably isn't the best way to diagnose a VSS problem. Besides, Cougar wants to complete diagnosis related to the temp sensor; when that's done, I can offer suggestions on diagnosing the VSS issue. Link to comment Share on other sites More sharing options...
Cougar Posted August 7, 2007 Share Posted August 7, 2007 Ok, we are on the right track. In order to measure the voltage you will need to put your meter leads across both leads of the sensor. Preferably while it is attached to the sensor. I don't know what a normal voltage will be unfortunately. The main thing is the voltage will be different when the engine is cold or hot. Link to comment Share on other sites More sharing options...
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