2000 Celica Electrical issues

[GasInMyVeins]

I'll let my posts from another site explain, rather than rewriting:

"Ok, so I have a 2000 Toyota Celica GT, manual tranny, just so you know. A few days ago, my gauge cluster went out. Speedo and tach (analog), odometer and fuel gauge (digital, boo) all gone. The various warning lights still work. No CEL has come on. The backlight for the HVAC controls, as well as the A/C are gone. It'll blow air, but never gets cold. Finally, the auto-on headlights don't work, though the headlights still work if turned on manually. None of the fuses are blown that I saw. I'm gonna double check that. It has around 127,000 miles (I'm not sure, as the odo is out). It did this once before in completely different weather and came back less than two days later. During the three days it has been out, it has come back a few times, after: disconnecting the battery for 20 min (worked once, didn't another time), wiggling the wires behind the cluster (failed after being left for a few hours), slamming the hood (cranked and worked once, not again, trying this again produced no results). I do have a 500+ watt sound system in it, but it's wired separately aside from the tweeters being hooked to the head unit via factory wires."
"I pulled the cluster and went over all the soldering and didn't see anything. I'm not at my house now (where it is) but I'll check again. I've seen a few things on the web about aftermarket alarms and sound systems causing problems like this in Toyotas, think that might be it? "
"I pulled the stereo. Didn't do anything. I checked all the fuses, all are good. I'll check the relays tomorrow (didn't have a voltmeter with me, someone want to tell me exactly how to do this??). Now every time I disconnect the battery, everything comes back. If I drive somewhere, it stays on until I shut it off, after which it won't come back. If I sit there after reconnecting it, I can turn the car on and off and have everything work for about two minutes. Also, every once in a while, when I reconnect the negative terminal, there is a sound from behind the dash. Sounds like a drill or something (my gf heard it both times, I was under the hood). After the sound the speedo needle swings to about 75-80mph and the tach to about 5500-6000 and both sit there twitching for 6-7 seconds. After that it behaves the same as any other time I disconnect the battery. I'm starting to think ECU. That's the only common connection. I read something online when searching on Google about a "body ECU," and I have a fuse labeled as such. What is that and could it be the cause?"

After way too much research, I'm about 85% sure the body ECU (which I now know is also called an Integration Relay) is to blame. My problem now seems to be finding it. So where is the damn thing?? And does that seem to be a logical conclusion? Thanks.

[catric69]

You can download the repair manuals here volume 1 & 2:http://www.newcelica.org/other/techn...ex.htm#manuals