Based on the 2000 wiring diagram posted by swartlkk above:


Assuming use of factory original (OEM) Control Switch and vehicle wiring here are the outputs to the mirrors on both sides:

You may notice that between 1997 and 2000, polarity for Right/Left motor control has reversed.
Also LT BLU has become WHT and GRY has become PPL/WHT and PPL/WHT has become RED/WHT

 

If the wiring diagram for 1996 is accurate, there are two wires for each motor coming out of the mirror (CONFIRMED! on my '96 Blazer mirror), so movement directions could be swapped externally. This would mean that the wires on factory original GM mirrors should be different between '96 & '97 even though the mirror is physically identical.

Since all of these mirrors work the same way, the only difficulty with retrofitting a '99 to '04 mirror to a '94 - '97 aside from untangling the color differences, is that the Right/Left control will move the mirrors in the opposite direction. There's no way to correct this outside the mirror because the Yellow wire is shared by both motors. You have to get inside the mirror and swap the wires where they're attached to the Right/Left motor (This is most likely not an option worth pursuing, since you'll likely break the mirror and not be able to get at the motors inside anyway.)

Edit: I just took apart my old '96 RH mirror and it's not possible to get it apart without a HIGH risk of breaking stuff. Also the sub-housing for the motors is plastic welded into place. It's just not a serviceable part. There's no access to the motors. I don't know if the 2nd style mirrors on '99 - '04 are the same that way, but pretty likely. The other approach is to see about modifying the switch.

 

So if you want to hook up the Power-Heated "2nd Style" mirrors of a '99 & later Blazer to a 1996 Blazer.

On the LEFT, door you'll need to attach:

Yellow (vehicle wire) to Light Green (mirror wire)
White (vehicle wire) to White (mirror wire)
Light Blue & Light Green (vehicle wires) to Yellow (mirror wire)
* remember that the LT BLU & LT GRN wires on '96 Blazers are electrically joined hence the same wire.



On the RIGHT door, you'll need to attach:

Yellow/Black (vehicle wire) to Purple/White (mirror wire)
White/Black (vehicle wire) to Red/White (mirror wire)
Light Blue/Black & Light Green/Black (vehicle wires) to Yellow (mirror wire)

Your Right-Left movement will be opposite of correct. You can either leave it this way or try to get inside the mirrors and swap the wires on the Right/Left motors. Leave Up/Down as they are. Up/Down should work correctly.

As far as hooking up the heating element and any other functions like electric self-folding or Night/Day switching, this will probably require installing your own wiring, fusing, relays and control switches.

 

So if you want to hook up the Power-Heated "2nd Style" mirrors of a '99 & later Blazer to a 1997 Blazer.

On the LEFT, door you'll need to attach:

Light Green (vehicle wire) to Light Green (mirror wire)
Light Blue (vehicle wire) to White (mirror wire)
Yellow (vehicle wire) to Yellow (mirror wire)


On the RIGHT door, you'll need to attach:

Gray (vehicle wire) to Purple/White (mirror wire)
Purple/White (vehicle wire) to Red/White (mirror wire)
Yellow (vehicle wire) to Yellow (mirror wire)

Your Right-Left movement will be opposite of correct. You can either leave it this way or try to get inside the mirrors and swap the wires on the Right/Left motors (I would not recommend this! High risk of breakage and too much work to be worthwhile).

Leave Up/Down as they are. Up/Down should work correctly.

As far as hooking up the heating element and any other functions like electric self-folding or Night/Day switching, this will probably require installing your own wiring, fusing, relays and control switches.

 

One thing you don't know from looking at product listings is that the 2nd Style mirrors of '99 - '94 Blazers have in internal metal structure (at least the ones made by TYC do.)

The mirrors that were on my '96 are all plastic and poorly engineered so as to break off easily. My right side broke off at the hinge so I used a large amount of epoxy to glue it back together, but recently as a result of exuberant door closure, the studs broke clean out of the plastic and the whole thing was left hanging by the electrical wires.

The 2nd Style mirrors are also bigger. Bigger, better and tougher. I'm liking it!

 

I just installed TYC part# 1000341 RH mirror on my '96 Blazer. It's one of the 2nd Style mirrors intended for '99-'04 Blazers.

This TYC mirror is heated. There are two black wires coming out of the mirror for the heating element. You need supply ground to one wire and +12V to the other. It doesn't matter which one gets GND & which one gets PWR just as long as one gets the opposite of the other.

The YEL wire is a common wire and shared by both motors. This is why you can't swap the wires to change the direction of the Left/Right motor without affecting the Up/Dwn motor.

Unfortunately everything that I published in the above postings is useless crap because the wire colors change at a connector inside the door, but prior to the connector where the mirror plugs in.

What works on the RIGHT SIDE is to connect:
YELLOW to YELLOW,
GRAY to RED
(PURPLE w/WHT Stripe) to PURPLE

I reused the old 4-pin connector body of the old "1st Style" mirror by removing the contacts from the plastic shell on the new mirror and inserting them into the old connector shell of the old mirror. I put one of the black wires into the 4th position. The other black wire had to remain outside of the connector body.

There are 2 yellow wires on the vehicle side and they are electrically the same wire, so I connected one of them to the single YEL wire on the new mirror and cut the other so that I could run it to GND.

I used an off-the-shelf bullet connector to connect a red PWR wire that I ran into the door from the REAR DEFOG switch PWR output to the other black mirror wire that was loose outside the 4 pin connector.

These mirrors seem to be reasonably good. They are fold-able and have 3 detents. They fold inward flat against the vehicle but not in the other direction. It opens up well beyond 90 degrees (maybe 120°) The middle detent seems a bit off as it holds the mirror angled inward too much and I have to adjust the glass outward quite a bit with the motors. Thankfully the glass does angle outward enough.

As mentioned above, they are heated. The heat seems to be concentrated in a small area in the center, but I haven't really tested this in ice & snow yet.

These particular units do NOT have the Day/Night auto-dimming feature nor do they have Power Folding. They are:

TYC Part# 1000342 LH (driver's side)
TYC Part# 1000341 RH

* 4-way Power Adjust
* Heated (2 black wires to electrical heating element)
* Manually fold-able
* Internal metal frame

I plan to take a look at the control switch to see if it can be modified to send the opposite polarity for Left/Right movement but since I'm not adjusting the mirrors very often at all, I can live with it being reverse of normal. Up/Down movement works properly as expected.

BTW If you decide to install these, don't forget to roll down the window so you can reach through to support the mirror. The mirror comes with 3 nuts and 3 separate flat washers and unfortunately you have to use them because the studs are larger diameter and the original nut/washer combo fasteners won't fit. Hold the mirror in place with one hand and get a nut started on the top stud so as to secure the mirror from falling, then you can fiddle with getting washers and nuts on the other two studs.

Sorry that all my diagrams in the previous posts are probably useless, but put some blame on GM for changing wire colors every time they pass a connector.

 

Here is a photo showing the new mirror electrical connection after I removed the 10 pin connector shell:



I replaced the 10-pin shell with the 4-pin shell from the old mirror.

You can see that I have the 3 wires that control the glass motion in the shell as well as 1 of the black heater wires.
The black heater wire in the conn shell will be connected to GND by way of a new black wire running from inside the vehicle (there is a grounding point next the lower right kick-panel), through the flexible rubber duct and into the door.

The other black heater wire is loose outside the conn. This one I'm connecting to PWR from the Rear Defog switch.




Running the wires for the mirror heater does require removal of:

Door-sill trim plate (Easy just lift off),
lower right side-facing kick panel and the lower plastic forward-facing kick panels
Instrument cluster bezel
Radio
Climate Control switch cluster

I'm upgrading my door and dash speakers at the same time, so the work of taking all this apart has a better pay-off than just getting heated mirrors. It's a good time to upgrade your sound system.

 

So here is what actually worked on my '96 Blazer. It doesn't match any of the electrical schematics or diagrams posted earlier in this topic. Go figure!

This applies to the following TYC '99 thru '04 "2nd Style" mirrors:
TYC Part# 1000342 LH (driver's side)
TYC Part# 1000341 RH

The Right/Left movement will be reverse of normal, but I've found no cost effective or reasonably easy way to remedy that. Wires can not be swapped at the mirrors or at the switch to correct this. Getting inside of the mirrors and swapping wires on the Left/Right motor would be difficult and very easily result in a broken mirror.



There are TWO Yellow wires going to each male mirror connector in the vehicle doors. You'll need to completely sever the 2nd Yellow wire about 1.5 inches back from the male vehicle connector and attach a Ground wire to the section of severed Yellow wire which is attached to the connector. This will supply Ground to the mirror heater via the 1st Black wire in the 4-pin female connector body.

This assumes that you remove the 10-pin connector shell from the new mirror and replace it with the 4-pin connector shell from the old style mirror as shown in the previous post.

 

Just a follow up. I am powering my mirror heaters directly off the Rear Defog Switch PPL wire. I've run the Rear Defog through 3 or 4 full cycles now and the 30amp fuse has not blown. The mirror heaters don't seem to use that much current judging from the wire size.