[BigAl70401]

Hello,
I have an '03 ZX3, auto-trans, 116,000 miles. Back in the spring I had problems with the transmission shifting from 2-3. Thanks to you guys at Focusfanatics I was able to avoid a $2,200 new transmission cost (which is what one guy told me). So, I replaced the SSA and SSE solenoids, filter, gasket, and fluid. That fixed the problem.
Now a new problem has recently started happening. Saturday while driving at about 30-40 mph I decided to turn the AC on. Man, my car started jerking, downshifting, etc. It was like it didn't know which gear to go into. Turn the AC off, problem goes away. Turn it on, it does the same thing. Also, the warning light comes on, but goes back off. Stop at a red-light, turn the ac on no problem, it seems to only happen while driving. Sunday, didn't have any problems. Today, Monday, was driving about 40 mph, decided to turn AC on, it happens again. Transmission goes crazy, turn AC off, the transmission is fine. Got home and parked, noticed that there is a clicking noise coming from under the dash while in D, and radio sounds like it's getting zapped. Took off the fuse panel and try to locate the clicking noise. It appeared to be coming from 1 of the 2 dark grey relays. So, popped the hood, disconnected the negative battery cable, cleaned the corrosion off of it, and let it sit about 1/2 hour. Re-connected the cable, started up the car and let it idle for about 10 minutes. Took it for a drive, turning AC on and off, no problems. But I'm pretty sure this is not over.
This sounds to me like an electrical short somewhere. I absolutely hate tracking down electrical problems in a car. I'm hoping that maybe another solenoid needs to be changed. It's much easier. Any suggestions would be greatly appreciated.

 

[whynotthinkwhynot]

What you were describing seemed to be a grounding or voltage loss problem. There should be a main large ground that goes to the engine or trans, 2 small ground wires, one goes to to the wiring harness, and the other goes to the chassis. Then there's a ground strap on the engine, near the back of the head on Zetec/SVTs IIRC, and a noise suppressor off the engine somewhere that grounds to the body. If you have a rigged ground terminal, you might even consider adding something like a 10 gauge ground to the transmission if you can find a place to screw one down.

Voltage drop conditions can also be caused by the positive, but the negative is typically the culprit. If you still have problems like this, then you might also be having problems with the battery going bad over 2-3 days sitting. That would indicate that something, somewhere is shorting and drawing juice.

 

[BigAl70401]

Thank you for the response. No problems with the battery losing juice. Sometimes it's parked the entire weekend and starts right up. Where can I find pics or diagrams of the ground strap, etc. that may be causing this problem?

 

[whynotthinkwhynot]

Check the easy to find wires first- those that go to the negative battery terminal. The ground strap comes off the cylinder head at the back of the engine and goes to the firewall. It looks like a metal shoelace. I have no idea where the noise suppressor is on that engine. Just look for a wire bolted to the metal chassis/body of the car.

The negative terminal wires are the most suspect IMO. Ground = negative- I hope I'm not confusing. I work with electrical every day so I flip flop terms but expect everyone to understand me like I was talking about chocolate chip cookies.

 

[BigAl70401]

Ok, got up this morning to work on the car, battery is dead as a door-nail. Jacked the car up to try to locate the battery ground, etc. I cannot find anything bolted to the firewall or chassis, or anything going from the cylinder head to the chassis, or anything going from the neg battery cable to the chassis, etc. I even put my glasses on! Can anyone give me a hint? Passenger side, driver's side? Pics, wiring diagrams? I'm clueless.

'03 ZX3 Zetec

 

[whynotthinkwhynot]

Follow the wires from the negative battery terminal. Those are the grounds. There should be a really big one that goes to the engine block or transmission. Then there should be 2 small wires. One goes to the body nearby, and the other disappears into the wiring harness- which is fine. These are the main grounds.

 

[BigAl70401]

I did find the ground coming off the cylinder head. It is attached to a bracket on the back of the head that sticks up above the valve cover. I thought it was something else. The other end is bolted to the strut tower behind the power fluid reservoir. Had to move that out of the way to get to it. Terminals didn't look to bad but wire brushed them anyway. My battery terminals were a little corroded so used baking soda and warm water to clean them, then wire brushed them. Had the battery on the charger for about 2 hours while I was doing all this. Put the battery back in the car, tried to start but it was still too weak. Hooked up the battery charger, set to Start mode, still couldn't get it started. Unhooked the battery and took it to parts store to have it tested. Went back an hour later and they told me it was bad, won't hold a charge. Got another battery (50%) off, installed it, started right up. I'll see if it's dead in the morning. I'm still not convinced this was the problem, but I hope it was. Stay tuned, and thanks for all the info.