Mechanics

IT BLOWS 4AMP STARTER FUSE WHEN KEY TURNE

2000 Toyota Camry

Electrical problem
2000 Toyota Camry 4 cyl Front Wheel Drive Automatic

If you start car by jumping starter, it blows the 10amp gauge fuse after a few minutes of run time. I have replaced the PCM, the neutral safety switch, and pulled the relay to the fuel pump. It still blows the 4amp starter fuse when ignition is in start position after all of that. The engine was recently rebuilt and all connectors are in their receptacles, and all grounds are hooked up. I idled the car for 5 hours with no problem, and drove it for 30 miles before this happened after the motor was rebuilt. The only problem that I was concerned with before this happened was that the temperature would have to get in the red before the cooling fans would come on. And the ac didnt work even though it did before the rebuild.
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Camry Owner 2000
May 8, 2010.




The fan switch is located at rear bottom of radiator. If unplugging the switch does not turn on the fans, bridge the terminals with a jumper to check if it does.

The starter fuse blowing indicates a short between the fuse, Neutra (PNP) switch and the starter relay.

Unplug the starter relay and PNP. At PNP wire connector, test for continuity between terminal # 6 and body ground. If continuity is present, the wire is shorted to body. Check for bruised wirings.

KHLow2008
Jun 23, 2010.
I replaced the one you spoke of and the fans still wont come on until red line. I believe that that one is the high temp switch. (As when I unplugged it the fans come on full blast not on low) The fans dont come on when when I unplug the low temp switch. Does that signify a short in that line, maybe? Also I did as you asked on the neutral safety switch no. 6 and a ground. I got continuity but only in an increment of full. Does that go directly to the starter fuse or starter relay, or does it go through the ecm first? I really appreciate your help, I feel we are going to find the solution soon.

Tiny
Camry Owner 2000
Jun 23, 2010.
I have checked lessened continuity when hot and it is good, so the low temp switch is not the problem. I checked voltage through the wires and it would only register just above zero. By the way when I first checked it, it was going up and down with I think spark from the engine. Is it possible for the spark plug wires or the coil pack to feed back through the low temp wires and blow the computer? After I moved the wires away from the coil pack it stopped surging. (It will shock you pretty bad when the engine is running) So what does it mean if no power is coming to the low temp switch? Is that the wire I need to track and see if there is a spot thats bad? Or could the computer be bad and causing all of the problems?(Because of feedback from coil) Because I have replaced the computer twice already so I was convinced it was not the problem. (But I was afraid of blowing the computer over and over because of another problem that needed addressing.)

Tiny
Camry Owner 2000
Jun 23, 2010.
Seems the coil pack is leaking and that is interfering with the wires passing nearby. You would have to check if the coil pack, soark plug wires or spark plugs are loose, or bad causing the spark leakage.

Problem should not be caused by the PCM but rather the spark plug wires and stray sparks.

If no battery voltage is present at the low temp switch, it means there could be a break in the wire and movements would cause intermittent failure. Yes, you need to trace the wire to check for possible breakages or bared wires causing the fuses blowing.
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KHLow2008
Jun 24, 2010.
I tested the low temp switch again and it is sending 5-6 volts, but I think it should be 12. Also if I unplug the low temp switch I think the fan should come on low but it doesnt. Any ideas like a resistor or somthing, I cant figure it out.

Tiny
Camry Owner 2000
Jun 30, 2010.
The fan is not a two speed fan and if they come on only when the gauge reading is high, possible causes are : 1. Temperature switch bad or wrong spec.

2. Gauge not accurate. When the gauge reading is high, does the coolant boil out to the recovery tank? Does the fans stop after running for a while?

3. Clogged radiator.

You mentioned the low speed switch, where is it located?

KHLow2008
Jul 1, 2010.
In response to not having two speed fan, I figured its voltage gets sent through a resistor, like the fan inside the car. That is how the fan could have a high and a low. Coolant does not boil out when the temp is high, but the fans come on probably just before that happens. Once the temp goes down the fans shut off till it gets hot again. Radiator flows well, no detectable clogs. The low temp switch is located right next to the temperature sensor on the tube exiting the engine or return flow to the radiator. (Not the water cock where the thermostat is located.) I have tested the resistance on the low temp switch. When cold no resistance, once operating temp is reached according to the temp gauge, there is resistance to the flow of electricity. I really think that there has to be a resistor in line that is bad, but I dont know how to find its location.

Tiny
Camry Owner 2000
Jul 2, 2010.
There are no resistors in the circuits but it consists of a few relays. I have emailed the schematics to you.

Since the coolant is not boiling over due to the high temperature reading, there is a possibility the temperatutre is correct but the reading is inaccurate, possibly due to a faulty gauge or sending unit.

Get a temperature gun to test the temperature of the coolant when the reading is high.

KHLow2008
Jul 2, 2010.

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