I plan to disconnect the battery in my car to do some electrical maintenance. Are there any electrical issues with the car I need to be aware of when disconnecting and reconnecting the battery? The only computer this thing has is for the fuel injector, but I don't want to blow anything up.

Is the proper sequence to disconnect the negative, then positive; reconnect sequence is positive, then negative?

After removing the rear seat and backrest to do some rust repair, I noticed what looks like a ground cable connected to the chassis behind the driver's seat where the bench seat normally goes. I assume that this is the ground for the fuel pump (?). The bolt looks kinda rusty so I was going to remove it, grind off the rust, apply some dielectric grease and refit.

With the battery disconnected, I also was going to replace the battery tray and hold-down hardware, wire-brush the fuses and the terminals in the fuse box and coat with dielectric grease, and install an ipd battery quick-disconnect.

Maybe working on the brick will cure some of my winter blues. :(
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Mike F - 1984 244 DL - 241,000 miles - Undergoing reconstructive surgery with POR-15

To the good advice below I would only add that you can expect a small spark and "zzzap" noise when you reconnect the battery's neg. terminal as your last step in finishing the work. This is because there are some electrical loads that may be still connected (clock, interior and/or trunk light, etc) and there seem to be capacitors that get recharged..or whatever.

I'm always a little surprised at the strength of that spark, but I've disconnected the batteries many times in many Volvos, and everything still works after, so it's normal.
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Bob (son's 81-244GL B21F, dtr's 83-244DL B23F, 'my' 94-944 B230FD; plus grocery-getter Dodge minivan, hobbycar 77 MGB, and numerous old motorcycles)

What freaks me out about the reconnection spark is the battery blowing up in my face. When jumping batteries, I fan the battery area in hopes of blowing away any gas hanging around before connecting the jumper cables. I don't know if this does any good or not.
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Mike F - 1984 244 DL - 241,000 miles - Undergoing reconstructive surgery with POR-15

That's a worthwhile safety procedure. And I always wear safety glasses when possible when working on the battery. Don't always have 'em handy when jump-starting a neighbor at Oh-Dark-Thirty AM.
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Bob (son's 81-244GL B21F, dtr's 83-244DL B23F, 'my' 94-944 B230FD; plus grocery-getter Dodge minivan, hobbycar 77 MGB, and numerous old motorcycles)

Radio code is the only issue, if applicable.
It is always worth cleaning any grounds, whatever they do. Something, somewhere, will seize the chance to malfunction if you give it a chance!

I've read too many stories on the brickboard about funky electrical problems that were eventually traced to a bad ground or dirty connections in the fuse box. I've been lucky with this car so far, and some preventive maintenance will hopefully keep my luck going.
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Mike F - 1984 244 DL - 241,000 miles - Undergoing reconstructive surgery with POR-15

Normal proceedure is to disconnect the negative terminal first and connect the negative terminal last.

The only reason you do this is so that the handle of your wrench won't spark if you touch it to ground while working on the positive terminal.

Otherwise, there is nothing to be concerned about that I know of. I presume that your car predates the anti-theft radios, so you don't have to worry about knowing the code when you disconnect your battery.

Yep, I still have the original stock radio with no anti-theft features. That's not a concern since I doubt anybody would steal it anyway.

Thanks for the other info.
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Mike F - 1984 244 DL - 241,000 miles - Undergoing reconstructive surgery with POR-15

Battery disconnection According to Haynes: Radio OFF (has a microprocessor that doesn't like to be 'bumped'); Engine OFF (no good for AMM/ECU?). I Think you're correct with fuel pump ground (check archives) whatever it is I think all BBers will attest: Volvo's just lurve having nice clean electrical grounds/contacts throughout! Good Luck.
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Mike's 'Indobrick' : '88 245 250,000kms; RIP: '84 360GLT 200,000kms.

The fuel pump ground looks kinda grumpy, so I better clean it and make it happy before it decides to strand me somewhere.

Thanks for the info.
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Mike F - 1984 244 DL - 241,000 miles - Undergoing reconstructive surgery with POR-15