[yeding]

hi, guys. I have a 00' prizm. I got hit at the front left side weeks ago, after the car was fixed, I noticed that my tail light, instrument panel illumiantion, as well as the gear shift illuminaton were all off. the fuse blown, but whenever I tried to replace the fuse, it blown right away. so I think there's short circuit somewhere. Mechanic wanna charge me 300 bucks for just check it for me. so I decide to do it my self. now, the thing is: in the fuse slot, the voltage is 12 V when I turn on the combination switch, which I think is normal. but the one of the connectors in the fuse slot is grounded no matter I turn on the conbimation switch or not, the resistance between this connector to ground is always less than 1ohm. I think without the combination switch on, that connector should not be grounded, so the short circuit is somewhere between the fuse slot and the combination switch. Am I right? according to the wire diagram I found on the repaire manual, the current goes out from the battery to the TAIL RELAY, and then go through the TAIL FUSE, and split in two, one goes through the INTEGRATION RELAY and finally get into the instrument panel illumination bulb; while the other one goes to the combination switch and then to the TAIL LIGHT. My question is: does the INTEGRATION RELAY controlled by the combination switch? without the combination switch on, the current can not get into any bulbs because of the switch or the INTEGRATION RELAY, right?
sorry for typing so much...... and thx for ur attention

 

[prizmatic]

Had exactly the same problem, 2000 Prizm driver's side front fender bender, had to replace the left directional/running light assembly, bang out fender, started blowing tail light fuses(15A), which of course knocks out the instrument panel lights as well.

After much circuit tracing, the problem turned out to be in the new bulb holder fixture in the new directional light assembly I bought from Rock Auto. If the wiring harness connector isn't pressed far enough onto or into the fixture that holds the bulb, something in the fixture shorts out the internal copper leads that power the running light from the green wire that feeds it from the wiring harness. Did it with the old fixture as well - the clearances in the bottom of the fixture under the bulb seem to be pretty close, and maybe that allows the short to happen. It will also short out if you remove the bulb while the tail lights are turned on. Know this sounds weird and improbable, but that's what I found.

The easiest way of troubleshooting this(rather than going through a pile of 15amp fuses) is to take a blown fuse, nibble away at the plastic ends enough so that you can solder a wire to the two tabs on each side, which when brought out will give you a way to measure current(if you like) or, better yet, to attach a 1 ohm 10 watt power resistor between the ends of the two wires from this made up fuse substitutor/circuit tester. Then if you turn on the lights manually and leave the car door open, the warning buzzer will sound and the tail lights will dimly glow. If there is a short, the resistor will get hot and the tail lights, etc. will not glow. Don't replace the fuse with a higher amp one or short the two wires on this made-up tester together, or you can do serious damage to the wiring and the relays in the tail light circuitry, which could make a relatively simple repair into a significantly expensive one. Tracing out shorts in the tail light circuit is a real challenge because it powers so many bulbs and devices, and this means of testing for shorts can really help.