94 3.4 running hot, no fans.
#12
08-20-2007, 08:58 PM
RE: 94 3.4 running hot, no fans.
Make sure all these things are okay:
Temp Sensor (sensor, not switch; there is one of each)
Thermostat
Relay/Fuse
Fan Motor
First thing I'd do is put direct power to the fan motor, if it comes on, it's good.
Then I'd check and make sure my thermostat was okay (atually I'd just replace it since it's cheap and would take more time to make sure it's ok than to replace.
I'd swap a relay I knew was good into the fans spot and then test.
Assuming all those things are in good working order I'd change the coolant temp sensor and electrical connecter (Napa# TS4015). Most people assume if their gauge works fine then their sensor is fine but the gauge relies on the temp sender switch and the fan uses the temp sensor.
If your fan still won't turn on, you got an opem circuit/bad wiring somewhere.
Hope this helps.
Temp Sensor (sensor, not switch; there is one of each)
Thermostat
Relay/Fuse
Fan Motor
First thing I'd do is put direct power to the fan motor, if it comes on, it's good.
Then I'd check and make sure my thermostat was okay (atually I'd just replace it since it's cheap and would take more time to make sure it's ok than to replace.
I'd swap a relay I knew was good into the fans spot and then test.
Assuming all those things are in good working order I'd change the coolant temp sensor and electrical connecter (Napa# TS4015). Most people assume if their gauge works fine then their sensor is fine but the gauge relies on the temp sender switch and the fan uses the temp sensor.
If your fan still won't turn on, you got an opem circuit/bad wiring somewhere.
Hope this helps.
#13
10-25-2007, 06:20 PM
RE: 94 3.4 running hot, no fans.
ORIGINAL: z28pete
Refill capacity:
I suspect your friend just drained the radiator instead of draining both the radiator and engine block, The radiator only holds about half of the total coolant, so when it was refilled it only took whatever the radiator could hold.
Fan not going on:
From the test you done it proves the power from the battery is getting to the relay contacts and that the fans are OK but says nothing about the control power to the fan relay windings, the relay itself, or if the relay sees a signal from the PCM. A quick way to test the whole system is to disconnect the wires from the ECT sensor (Engine Coolant Temp Sensor not the temp gage sensor, they are two different things). Put a jumper (resistor)between the two wires (YEL & BLK/PNK) going back to the PCM (use a 100 to 200 Ohm 1/4 or 1/2Wattresitor, from Radio Shack, to protct the PCM). This will simulate max coolant temp and the PCM will request the fan to operate. If the fan operates you probably have a bad sensor or the coolant is not getting to the sensor. If the fan does not come on, you probably have some wiring/connector problem somewhere from the sensor to the PCM, or from the PCM to the fan relay.
If you have a scan tool you cam monitor the coolant temp and PCM reaction as youjumper the leads, if it shows hot you are good to the PCM and the PCM is seeing the high temp. If the PCM is working as it should,it will send a fan ON request (ground to the fan relay control lead).
Refill capacity:
I suspect your friend just drained the radiator instead of draining both the radiator and engine block, The radiator only holds about half of the total coolant, so when it was refilled it only took whatever the radiator could hold.
Fan not going on:
From the test you done it proves the power from the battery is getting to the relay contacts and that the fans are OK but says nothing about the control power to the fan relay windings, the relay itself, or if the relay sees a signal from the PCM. A quick way to test the whole system is to disconnect the wires from the ECT sensor (Engine Coolant Temp Sensor not the temp gage sensor, they are two different things). Put a jumper (resistor)between the two wires (YEL & BLK/PNK) going back to the PCM (use a 100 to 200 Ohm 1/4 or 1/2Wattresitor, from Radio Shack, to protct the PCM). This will simulate max coolant temp and the PCM will request the fan to operate. If the fan operates you probably have a bad sensor or the coolant is not getting to the sensor. If the fan does not come on, you probably have some wiring/connector problem somewhere from the sensor to the PCM, or from the PCM to the fan relay.
If you have a scan tool you cam monitor the coolant temp and PCM reaction as youjumper the leads, if it shows hot you are good to the PCM and the PCM is seeing the high temp. If the PCM is working as it should,it will send a fan ON request (ground to the fan relay control lead).
#14
10-28-2007, 03:22 PM
RE: 94 3.4 running hot, no fans.
I dont understand why you are making yourself so crazy for such a simple problem. All gms are notrious for that fan switch to go bad. All you need to is jump the positive wire to the fan and run it to the fuse box under the hood. Take a volt meter and find out which links give you power only when the ignition is on. Once you find one use a fuse tap and tap that fuse. Problem solved. If you are afraid the fan will draw too much then use a relay and voila problem solved.
Thread
Thread Starter
Forum
Replies
Last Post
orlando_trudeau@yahoo.com
93-02 V6 Tech
9
06-16-2009 12:35 PM
