Thread: Elusive Electrical Problems

I posted pics mostly of OBD readings and a video of engine attempting to run normally.

Microsoft services

Information:
1. Per the upstream O2 sensor: it wouldn't come out and the wires severed at the tip so I disconnected it. I tried connecting another one and covering it, but it doesn’t change anything. At some point I'll replace the header/sensor but I doubt that's the source of all this erratic behavior. It should be running open loop without the O2 according to my research.
2. Cooling fan errors can be ignored: I jumped the relay to switch them on when I see fit because otherwise they don't come on til 225 or whatever it is which is too hot.
3. Replaced VSS (502 error) with a junkyard part but nothing changed at all.
4. I looked all over the wiring harness for exposed wires and shorts, only place I found that was by the PCM and some of them looked like they had been eaten by a rodent. I repaired and shielded them but the only result was the speedometer came back online.
5. The TAC 2107 and solenoid 1860 errors I thought would resolve by fixing problems with the wiring harness but car still running poorly, as said nothing much changed.
6. Low beam relay was clicking every time battery died, and still did that after I swapped the 8866 relay. Low beam headlights keep going out very quickly. I get them from the junkyard but they burn out about once a month. I don’t see a wiring problem visible there either.
7. Battery normally checks at 12.6 when not dead, and 14.6 while car running. I tried to drain test by bridging connectors with terminal on amp several times and each time there's miraculously 0 load, even when I open a door or turn on the key. I also pinned the meter on both sides of each fuse and none had load with car off. All of which seems impossible, since the battery drains and usually doesn’t start without boost, even minutes after running for a while.
8. It's a 2004 Grand Prix with 195k miles and I'm the only mechanic I can afford. I can’t afford a new car either. This is it.

Problems still existing:
Engine RPM fluctuating drastically, except when idling after a minute of warmup (tac?)
Sputters on acceleration without delivering much power (tac?)
Hard time starting especially when battery mysteriously drains (solenoid?)
Battery keeps getting drained or shorted. (no idea anymore)
.
Anything you know that will help is appreciated.

If you have found ANY wires that have been, or looked like they have been eaten by a rodent,... chances are there are more wires the with the same problem, you just have not found them yet.

I have not had rodent problem eating wires on my car, but I have had chaffed wires cause problems. Solution: disconnect PCM and check continuity on every pin from the PCM connectors to each individual wire destination, be it sensor, relay, bulb, ect. You may be able to narrow it down by subsystem following a wiring schematic, that is what I did. It's the only way to be sure you dont have a broken, or partially broken wire/wires somewhere. You have to be absolutely certain there are no breaks in the wires before you can continue diagnosing.

For the record, I have no idea how a rodent would get into the air filter assembly and then feel the need to start chewing wires to get out a different way then it came in, but it might have been holding on to them for dear life and then got sucked into the throttle and into the engine and that would explain why suddenly it has so many problems. I pulled the throttle body and it looked fine visually, good action.
The battery is about 6 months old and is the 3rd replacement on a Walmart 2 year battery warranty and I think it's still good as it tested a month ago to be fine, unless recent stuff killed it.
I just posted all the errors from OBD, including the P480 which was apparently the only thing I could get freeze frame data on, no matter how many buttons pressed on the scanner.
I like the idea of putting the sensor in the cross pipe but right now I need to solve these massive electrical problems.
Right after I posted this I saw other posts suggested and people said similar problems were ignition switch. Does anyone suppose that the ig switch or other items could have been injured by the shredded and crossed wires shorting things out? Even if the wires are perhaps fixed now.
Also does anyone think it's possible that a car can have a hex put on it? Because it was fine for 15 years but the past year at least 300 things have gone wrong.

So you guys are saying I need to plant the mousetrap first then go from there?
I'm pretty sure the offending mouse got sucked into the throttle and became fuel.
But seriously if there's a good way to test the ignition switch, tac, or solenoid I'd be happy to do that before investing more.
I did the standard load test with two different meters and they both had zero. Just bridging the neg terminal with the connector not rocket science. No amps appeared under any circumstance which I think is impossible and thus somebody put a curse on the car.
I heard if I get the head of a live rooster the curse can be removed. Any truth to that?

The first thing I suspected with multiple sensor problems was wiring, so I checked it and saw nothing until I pulled the air filter and saw severed wires. Even before that I wanted to replace the entire harness but a few dollars short. And I replaced the speed sensor because it was easy and didn't cost anything.
So my meter had a blown amp fuse and I fixed it. Able to do drain test. I posted pics in the same link above, but get this.
Soon as I hook it up, it reads. 0.85 amps for about 15 seconds then goes less than 0.05. So I pulled fuses during each 0.85 interval and then disconnect and reconnect and pulled more. One fuse made it immediately go down to normal. The battery main fuse 1. I pulled it several times and watch the amp drop then go back to 0.85 after plugged back in. Doors opening did not change the load, but...
Another thing I've noticed is the battery dies if a door is open for more than five seconds... Which makes no sense since I pulled the interior light fuse a month ago and they don't come on at all.
For example, today I charged battery, drove five minutes to gas station, returned in ten and it started right up. Drove back and opened a couple doors to unload cargo and it was already dying with the clicking not enough amp sound trying to start it.
I can't make heads or tails of it. There is a pattern to the behavior but not one that I recognize.

It's well known in my car that continued arming and disarming of the anti lock theft system eventually kills the battery and combined with usage of anything like windows or radio or inverter with the car not running, usually kills the battery within a year. This being the last battery in the warranty replacement, I haven't been doing any of those things except using the auto locks. No corrosion, everything is clean and tight. After charging the battery today, I put on the volt meter and saw that it took only a few times using auto locks on and off for the meter to go down below 10v.
Good news is I fixed the wild rpm fluctuation issue, as it was what I thought it was initially, the tube that runs from the front of super charger around rear to a wiring socket behind it. Because I had broken it on the side a couple years back, and it did the same thing. This time it was disconnected at that rear socket where I couldn't see that it was hiding right beneath it without actually being connected. But I was inspecting the wiring again and saw it was out of socket. Now my rpm and mpg are back to normal.
Anyone know what those two wiring sockets are in the rear with the SC tube running to one of them, and what the tube is? I have included a picture, but that being disconnects causes wild RPM and bad MPG alone.
Bad news is auto shops aren't loaning the OBD tool anymore so I don't know how they are figuring out what's wrong with anything, so I have to drive across town to borrow my brother's, read and delete codes, and drive cycle again. Car still misfiring and sputtering on acceleration but cruises fine for now.
Meantime I'm trying to find some wiring diagrams and will go thru entire PCM pins or attempt to. I don't even know how to do it but I'm sure somebody does.

That's why it takes me so long to describe it. Why does one map sensor work fine alone but the other freaks out without its air tube attached? Is it asthmatic?
I think there's some hope here but I was wrong thinking all problems were related since they started at once. Instead, a hundred different problems all started this year.