Pickup wiring issues

I have a Squier P Bass that I've been using for years and finally decided to replace the pickups, pots, cap, and input due to an unexpectedly new position in a praise band. I don't have much experience with changing out parts, so keep that in mind.

I un-soldered everything, taking pictures along the way so I would remember where to solder the wires for the new parts. I wired it exactly the same way with the new parts. After putting it back together and restringing, I was getting sound, but the volume was way to low. Both pots seemed to work, just no volume. I took it apart again, thinking I needed to resolder everything. I tested it again to make sure I was right and sure enough, it was much louder than before (pickguard/wires hanging out). I'm not sure if it's full volume yet, that's the problem.

Something was wrong when I screwed it back together. I don't know what to do next. Should I get a multimeter to check the solder connections? Put it back together and hope for the best? Any advice would be much appreciated.

I decided the volume is full now with the wiring out. Now when I try to install the pickguard and push down the section with the pots/input, the volume cuts out again. I don't know what is causing this, and I'm sure some of you do.

This sounds like a minor short circuit. Maybe the insulation on some "hot" wire is punctured and touches the grounded part like pickguard - it's probably covered with a grounded shielding on the inside. Is the pot chamber naturally "woody" or it's covered in some dark paint-like substance? If so, the substance's also a grounded conductor. When a "hot" wire touches grounded part, there's a short circuit that usually cuts the whole signal, but sometimes just reduces the volume.

Also, standard procedures: make sure the bridge is properly grounded.

OK, here's the deal. The pot chamber is covered in black paint, so I decided it must have been a short circuit causing the volume drop. I did something stupid when I originally soldered it and used (forgive my horrible use of guitar wiring terminology) some strands of wire from a wire originally covered in black with a copper center to go from one of the 3 "lugs" on the volume pot to ground it to itself (I think that's what it does). I decided that must be the culprit, so I exchanged that wire for one of the wire "legs" of an extra cap I had, since that what it looked like in the original pot.

After putting everything back together, it seemed to work alright. There were two problems though. After playing for a while, I determined the volume was nowhere near where it used to be, but still much higher than when I was getting the short circuit. I don't know what is causing this. Secondly, the pickup height, which you can see in the picture, is much lower than it was with my old pickups. I can barely rest my thumb on the pickup cover now. When I try to raise the screws, all it does is loosen the pickup; it seems to be as high as it goes. I must be doing something, or several things, wrong.

Does anyone have any other ideas, or should I take this to a professional to get it looked at? Let me know if you need more pictures.

The first picture of an individual pot was the tone pot. This is the volume pot.

This sounds like a minor short circuit. Maybe the insulation on some "hot" wire is punctured and touches the grounded part like pickguard - it's probably covered with a grounded shielding on the inside. Is the pot chamber naturally "woody" or it's covered in some dark paint-like substance? If so, the substance's also a grounded conductor. When a "hot" wire touches grounded part, there's a short circuit that usually cuts the whole signal, but sometimes just reduces the volume.

Also, standard procedures: make sure the bridge is properly grounded.

When you say "make sure the bridge is properly grounded", what do you mean? Should I unscrew the bridge and make sure the black wire is soldered to it? Should I resolder the black wire to the pot? I'm sorry, I am a novice at these things.

Usually, there's a thin cable running through the wood between the pot chamber and bridge. It goes from the ground cables on the pots and "resurfaces" underneath the bridge, touching it's base. It closes the circuit, so the strings are better... well, "picked up" by pickup. :D

Fender wiring diagram for P-bass
http://support.fender.com/service_diagrams/bass_guitars/019-3200_02A_SISD.pdf

The hot pickup wire goes to top of vol pot, its wiper goes to the output jack.
I believe you have this reversed.

The tone control connects to the top of the vol pot too. Rather like a tele without a selector switch. The cans of the two pots must be connected together by a ground wire, do not rely on the shielding, to which the pickup cold, jack cold and bridge/hardware are also connected.

Reguarding pickup hieght, pull the pups out and put some foam under them to hold them up. I had the same problem with my fretless when I installed the pups. I used a piece cut the size of the pup and about 1/2" thick. This should also make your bass louder.

New pickups are usually supplied with the foam.

When you say "make sure the bridge is properly grounded", what do you mean? Should I unscrew the bridge and make sure the black wire is soldered to it? Should I resolder the black wire to the pot? I'm sorry, I am a novice at these things.

Test the bridge to ground continuity with your meter.

I dislike the normal "loose wire" method, so yes, depending on fixing I dismount the bridge and fit a solder eyelet tag which one of the screws will go through, the small flat solder joint buries into the wood with pressure from the bridge, or assist with hammer. On one tele I soldered the wire to the plate with a gas torch, not a novice job unless you like discoloured chrome.

Putting too much heat on a pot can, often cooks the pot to useless, use a big iron and do it quick. Heat is heat capacity, not temperature, hence a big soldering iron >45W.

I ended up using some foam from the old pickups to boost the height and that seemed to solve the problem. Sounds good now. Thanks for all the help, everyone. Ready for the next project.