Question(s) about Step-Down Butt Connector Splice

I am in the process of installing a DC Blower Motor connector and repair harness on my 04 AC and being a beginner on the electrical side had a couple of questions before getting started.

For this job, I am using a 12-10 ga/ 8 gauge step-down connector to splice the 8 ga DC pigtails coming from the DC female BM connector to the two 12 ga BM harness wire coming from behind the glove box. The harness wires consist of: a) blue with red striped wire; and b) blue with black striped wire. Both are 12 ga.

The SD butt connector that I am using looks like this and has two inspection windows.



12 ga side


8 ga side



Q1) Most vids I've seen say not to strip more than 0.25 in off the wire end before inserting into the butt connector. While doing a test splice using the SD connector, the 12 ga side was stripped slightly more than 1/4 in while the 8 ga was stripped until visible in its inspection window, which was more like 0.45 in. Which technique is correct in the pic below? In one, the 8 ga wire is seen coming up the center tab while the 12 ga is not visible.



Both connections are solid and not going anywhere even though the die indent or stamp is much cleaner on the 12 ga side as seen below. Visually, I am not as happy on the 8 ga side.









Comments on the crimps?

Q2) Does it matter which pin side of the female connector the blue/red striped wire (with box terminal) and the blue/black striped wire go in? I don't want to make a stupid mistake and fry something. The fan rotates counterclockwise too, if that matters.

In the past, I used 1/4 in female quick connects to attach to the DC blower motor and kept the Blue/Red wire to the inside (toward the glovebox) and the Blue/Black wire to the outside since that is how they seemed to exit the harness.

Q3) When the old blower motor went out, I caused it to arc badly while tapping with a tool in the dark. I guess the wires were stretched and/or burned beforehand and I knocked the 2 wires together. Some of the plastic at the base of the male connector mounted on the old BM was melted and the wire ends were frayed. Is there anything to check other than the BM resistor and the fuse or relay if the new motor does not crank up?

Any helpful insights are appreciated.

 

Can you get some photos from the truck too?

I’m tempted to suggest crimping rather than splicing to step down.

 

Give me a minute to post pics.

 

On the Access Cab and Standard Cab blowers, Blue with Red stripe is +12V and Blue with Black stripe is ground.



On the Double Cab, the colors are Blue w/ Red stripe +12V (pin 2) and Blue with White stripe Ground (pin 1)



Note that pin numbers are looking at the front of the connector, not the side the wires enter. You need to match up positions or you will likely have problems - at a minimum the blower turning backwards...

As for crimps - I would strip insulation so that the bare wire fully enters the connector to the stop. You don't want insulation inside the metal crimp barrel but you also don't want exposed wire out of the barrel.

 

So this is the 12 ga wires coming off the harness....maybe 4 inches or so from harness...blue/red and blue/black.




Also, that's just the old blown motor with a trial set-up that I initially thought about using with insulated female disconnects as shown below more clearly. I have used this setup before except uninsulated.



Then I decided to go OEM connector and repair harness (8ga) using the setup below.



This is what the current setup will be absent the heat shrink step-down butt connector which will be installed.

 

Looking at the front of your new connector so it matches the photo in my post, you need to connect the wire in position 1 (left hand) with the Blue/Black stripe wire in your truck. That is the ground (which also is how the blower motor is switched/controlled).

The other wire on that connector goes to the Blue/Red stripe - it is the +12V power from the heater relay.

 

So the wire marked with the red tape is in the correct position when matched with the blue/red coming off the harness, then?

 

Also, should the stripped portion of the wire extend to the window as shown in an earlier post or just kind of touch up against the arched metal tab which makes it hard to know if the wire is being stopped at the tab or by the insulation at the barrel entrance.

Heat shrink trial run...

 

Thanks, Casey...I needed that good info to move forward. Jay.

 

Like Casey said, I'd strip a bit more off so when you push the wire in, just a bit off copper is showing. When you crimp it it will squeeze some of the butt splice back towards the wire. Also, 2 crimps is better than 1. Rotate your 2nd crimp 90° to the first.

 

No idea
I can’t make out the orientation if the connector in that view.

 

This may be a total opposite/diversion from others, but in this exact case, I'd really recommend using solder w/method #1 here and heat shrink. Specifically using method #1 when pairing the wires. (don't forget to slide on heat shrink before soldering)

Using this method, there's never a concern the two will pull apart, you won't have the janky buttsplice look to things, and there's no real "step-down" involved.

I'll post a more OEM-like method in a reply following this one, I just need to dig up a picture of what's inside Toyota's front door harness for the 1st gen AC/RC truck speakers.

​

 

This one is purely to show what Toyota does in a similar OEM situation. In this, they're taking a two-wire feed (front speaker channel +/-) and forking it out to two channels, using the same gauge wiring for all three wires (i.e. double thick on one side, not quite identical, but similar).

In this case, they're using a simple non-insulated connector (so again, you'd want to use heatshrink) like THIS or THIS (TE makes in many diff't gauges), sliding the wires into the barrel in opposing fashion, with 2mm-3mm overhang, and crimping.

​

 

Oh, and one more pic I forgot to post of the above soldering method.

With this, you won't pre-tin the wires and don't need to use rosin/flux/paste. Once the wires are twisted, you're going to lay the tip of your heated-up iron at the middle of the twist for 5-10 seconds, then touch the solder to the other side of the twist from the iron. I like to prop the iron tip behind my wire twist, then tap my solder strand to the front of the twist. The heat from the iron will - with patience from the operator - pull the solder thru the wire and tie everything together. That's the way to do it properly, you do not want to simply drop melted solder on top of the wires. Make the iron and the wire weave do the work for you. Capillary action will cause full penetration.

​

 

Soldering an 8awg wire is no joke.

 

Just takes a little longer to pre-heat. Very doable, without melting the OEM sleeve, though.

If it were me, I'd personally just buy the proper crimp-on ends, and terminate my OEM wires (assuming there's enough wire length available)

 

I would crimp myself

https://www.corsa-technic.com/item.php?item_id=1015

assuming that is the proper terminal.

 

Butt connectors sort of make me sad resistance-wise for large gauge wire. But that is irrational, I’m sure it’s fine.