I tow a 2004 GMC Envoy behind my RV. Key must be in ACC position to unlock steering wheel. At the end of the day my battery is run down from dash lighting usually needing to be jump started. I installed a battery disconect. When I disconect the battery I loose memory in PCM. When I reconect, PCM takes several days to reset. Engine runs bad until PCM resets. What alternatives do I have other than battery disconect?

welcome to USA forum
the country with not ONE< JIMNY,
but i can answer
there are 4 ways to tow this is but 1.
backwards towing is best way or drop rear drive shaft (ask)
flat tow 101:
the Jimny is SJ413 here,called Samurai.
the transfer case sets this rule (most rear device)
that rules is dont flat tow it, more that 200 miles
the rear bearing has no lube actions towed
here is the near same transmissions.

and rules (of xfr case)
ill quote my 2001 Vitara, (same setup.)

Follow these steps:
1. Set the parking brake.
2. Shift your automatic transmission into PARK (P), or
your manual transmission to SECOND (2).
3. With the ignition key in the ON position, move the
transfer case to NEUTRAL and make sure the 4WD
light on the instrument panel cluster is off. See
"Four-Wheel Drive" in the Index.
4. Turn the ignition key to ACC to unlock the
steering wheel.
5. Release the parking brake
If you tow your four-wheel-drive vehicle from
the front, make sure to move the transfer case
into NEUTRAL or your vehicle could be badly
damaged and the damage would not be covered
by your warranty.
Stop towing every 200 miles (300 km) and start the
engine. Leave the transfer case shift lever in
NEUTRAL. Shift your automatic transmission to
DRIVE (D); leave a manual transmission in
SECOND (2) with the clutch engaged. Run the engine at
medium speed for one minute to circulate oil in the
transfer case. Turn the ignition key to ACC. Now, you
can continue towing your vehicle.
The front wheels transmit shocks during towing.
The steering column may not be strong enough to
withstand the shocks. Always unlock the steering
wheel before towing.
Make sure that the towing speed does not
exceed 50 mph (80 km/h), or your vehicle could
be badly damaged
end direct quote operators guide .....
got that?

not how the 5speed box is in 2nd.
this is to keep it from spinning, and its rear bearing damaged.
there are 2 bearings to worry the rear 5sp and rear transfer case.

on ours, we use an electric oil'er pump added to transfer case.
unlimited tow. (wires power feed from RV via coupler.)
or the drives shaft decoupling device, (not cheap)
or we drop the rear, of prop shaft, and tie up the rear up high
so it cant drop nor let it fall of rear of transfer cases
we use bunji cords, for up,
and then pull the front,
if the prop shaft falls out, you will lose GL4 gear lube out rear
of the transfer case. it falls out so very easy, off that spine.
there are all ways flat,
done them all.,

If you have to have the key on to unlock the steering wheel, try installing a battery cut off switch under the hood. You cannot completely remove battery power completely or you will loose the radio station memory and the brake lights. You can install a battery isolator on the RV so you can charge the battery on the odessy while you're towing it using a wire on the hitch connector.

Lots of possibilities, but based on the information you've given, the most likely scenario is that the battery voltage has dropped too low to engage the starter. It may still be strong enough to turn on dash lights, interior lights or even headlights, but those draw far less power than the starter. That is assuming it is not 'turning over' based on you saying it will not start. If it turns over (cranks the engine) normally, but still will not start, then that is different. The gear shift on most vehicles will move if you have the key turned to the on position, but I cannot be positive about a 2004 Envoy, so that part seems a bit odd. The steering wheel should be unlocked when the key is in the on position, so that part is normal. If it is a battery problem, that could have been caused by some other issue (failed alternator, for example), or could have been as simple as lights being left on. I hope that helps.

make sure its in park, move the steering wheel back and forth a llttle. check the electrical part of the key switch.

I know sometimes when the steering wheel locks it sort of causes a bind. Try moving your wheel back and forth as little as it may be and turn the key at the same time see if it unlocks and turns then.

No we can not tell you which fuse because there is no fuse to pull.
If you do an internet search for "tow a blazer behind an RV" you will find the procedure to put the transfer case in neutral and take it back out when you want to drive the truck. Its about 10 steps using the 4wd buttons on the dash.

I don't have towing specs on yours, but I have never seen a requirement that the key be "on" unless there is a position where the wheels are free but the electrical system is not on. The steering needs to be able to turn, but having the electrical system on, it's possible that the abs system is somehow locking up the wheels (reading wheel speed and comparing it to no driveshaft speed) To verify my theory, if it's impossible to not have the key all the way on, I'd try pulling the abs relay or fuse and see if it still happens. Also, on long tows with the electrical system on you may need to re-charge the battery (another reason I can't understand why they would tell you to have the key on)
Good luck with this...perhaps an rv guy will pick up on your post and give you a better answer.

Most cars are about 1/2 ton capacity(1000 pounds) Towing a small trailer should be fine as long as the weight at the hitch ball is less than 200 pounds. Load the trailer so the most of the weight is on the trailer not your car.Remember to keep the tire pressure correct on the trailer and your car and give yourself plenty of stopping space as the car will respond slower with the extra weight. Also try to take off kind of slow and easy so you dont over work your cars transmission. An add on type auxillery transmission cooler is recommended.
I hope this info helps you.

I've found that the steering lock on some vehicles will interfere with the ignition lock and the steering wheel may have to be rocked to find the right position.
I think the purpose of this was to ensure that the steering lock is engaged before you can take the key out; don't ask me why - if the key is out and anyone tries to steal the car, the steering wheel will find the pin the first time the wheel is turned 90-180 degrees anyhow.

get in truck shut door . . . turn key to acc position. . .push alarm button on dash near ECT button. turn key back off .. . then to the acc position again. . then push button back like it originally was. this should help i had the same problem . only i was in the middle of the woods with no cell phone signal!