i pulled the covers off the fan relays and they aren't actuating. whether the motor is warm or cold, i get 12 volts across the coil terminals on the relay plugs when the key is in the running position. jumpering the contact terminals makes the fans come on. replacing the relays doesn't solve the problem. i get around 70 ohms across the relay coils in both the new and old relays. i'm totally stumped, as all the electrical readings seem normal to me. since i can make the fans come on with the jumper, i can also rule out problems with the fan motors.
2006-09-09 07:11:24 · 4 answers · asked by Anonymous in Cars & Transportation ➔ Maintenance & Repairs
You're checking the wrong terminals on the relay...if you always have 12 volts (and resistance) across the terminals you check, then you are checking a circuit that is normally closed when the fans are supposed to be off...of course if you jump across these terminals the fans come on, only problem is they would never shut off.
The relay has a gate in it that should electrically move the contacts so that power changes it's flow between the terminals. You are not getting 12 volts to the terminal that controls this gate. Look on the diagram on the relay...terminals 30 to 87a are normally closed...when power is applied to terminal 86, the gate swings and terminals 30 to 87 are closed. You are having a problem getting 12 volts to terminal 86...likely a broken wire somewhere in the circuit.
2006-09-09 07:27:17 · answer #1 · answered by boobatuba 3 · 0⤊ 0⤋
You are fighting a reverse battle. You will always have power to the relay, and the fans. The problem is, that the relay is used to control the fans because the fans draw too much power for the PCM to control. The PCM controls the fans when it senses
1) Temperatures rising or
2) When the A/C is energized.
If you can start your car, open both doors, and turn the A/C on MAX, if the fans don't run, there is a plug or sensing connection loose to the PCM and control circuit.
If the fan does come on here, then most likely the temperature sensor for the computer (NOT the gauge) has failed, and is telling the computer that the engine is within a safe range.
Ideally, you could use a wiring roadmap and a "trouble tree" for diagnosis from a repair manual. You don't have to necessarily buy them. You can check at your library, or log onto one of these sites. But you should know, both of these sites are subscription.
good Luck
http://www.eautorepair.net/
http://www.alldatadiy.com/
2006-09-09 15:32:57 · answer #2 · answered by Ironhand 6 · 0⤊ 0⤋
Since all the voltage wires are showing good and the motor is good,the next step would be to check the connector and voltage from the connector to the fan.check from the neg battery cable as the ground when checking this voltage and if it reads good then I would say that you have a faulty ground..
2006-09-09 14:17:58 · answer #3 · answered by jlthomas75844 5 · 0⤊ 0⤋
defective thermoswitch.
2006-09-09 14:14:26 · answer #4 · answered by Anonymous · 0⤊ 0⤋