How to wire up a NP 236 in place of a 136.

[WoodButcher]

I've been told that the bravada and astro share the same drive train, 4.3, 4l60e and so on as do the S-10.
Give her a shot and let us know.

[MountainManJoe]

I think the Bravada had a BW4472 (same as early Astro. no electronics), then NV126 transfer case (lighter duty version of 136) or 226 (like 126 but with low range).

S-10 had NV231, 233 (part time 4WD, not AWD)

Blazer/Jimmy had the 236 in this topic (2-speed version of the Astro 136)

The 136 is exclusive to the Astro.

It will vary year to year though.

[tanvanmanwithaplan]

Hey y'all from mid Missouri. 2001 Astro AWD 2+1 235/75/r15 Grabber ATx 169k miles had it since 2013 112k miles.

I have bolted up a 78k mile junkyard NP236 and RTV is curing before I fill it, went pretty smooth except gasket material removal.

About to start wiring. I have the following:

• NP236 TCCM + both plugs w/6" wire left

• Blazer 4 button switch + both plugs w/6" wire left

• NP236 case side wiring harness with all plugs and about 3 feet of wire

In order to make the connections of VCM--->ECU and for the axle disconnect emulator circuit, do I need to go back to JY and grab ECU and VCM plugs to have extra pins? or are these pin types shared with the TCCM and I can just use those?

Also for repinning, is a straight pick good enough or is there a better tool I should grab?

I am trying to get this online by the end of the weekend so I can be on schedule to test, finish solar and leave for Colorado by June1

Thomas

[tanvanmanwithaplan]

In order to make the connections of VCM--->ECU and for the axle disconnect emulator circuit, do I need to go back to JY and grab ECU and VCM plugs to have extra pins? or are these pin types shared with the TCCM and I can just use those?

Answer: I think I need JY parts

Also for repinning, is a straight pick good enough or is there a better tool I should grab?

Answer: Bobby pin with ball clipped off one side is the ideal tool for the TCCM pins.

Update: I've been juggling progress on this with my job, but I've got wires run soldered between TCCM and transfer case. I have mixed up which speed sensors go where on the TC, going to figure that out later by wire color. Hoping to wire up the switch late tonight or at least get some good progress on it, then go get a relay and ECU plug from the JY tomorrow.

[Herbie]

Also for repinning, is a straight pick good enough or is there a better tool I should grab?

When I added the pin for the 4-Low signal to my ECU, a standard Pin Insertion/Removal tool made the job very easy: https://amzn.to/3uRB8hk

For <$5, hard to beat.

[tanvanmanwithaplan]

So, having a 2001 AWD astro LT, if I get ECU plugs with pigtails from some other 2001 era chevy full size I will get the pin I need? For example a Tahoe, Silverado, Sierra, Suburban?

My van has two really long plugs on the ECU running vertically.

Thomas

[Herbie]

You can see a few photos of what it takes to put the pin into place on my blog here: https://herbiesworld.blogspot.com/2017/ ... -with.html

I wouldn't mess with getting the whole ECU connection set unless you really have no other way to harvest/buy the pins you need. Heck, at my pick-a-part yards, the ECUs and attached plugs are often the first things to get cut out. If you do find one, though, you could use the removal half of the pin tool I linked above to pop a few pins out of an ECU plug - my local yard would definitely let those go more cheaply than the whole plug assembly.

[AstroSurf]

Hey folks,

Lurker and follower of all your work and knowledge.

I’m another follower of Capn Crunch and racrx7’s pioneering ways…

Got my 236 wired up last week, I thought. Got it working, and switching into all gears one night, the next day I came to clean up the wiring and put everything back together, and I had no function.

I’m using the tall switch from a 2001 tahoe wired like so:

TC Switch Wiring

C1 (black) to TCCM
A - Ground (black)
B - E3 (pink)
C - F3 (dark brown)
D - Blank
E - Convenience Center - B (purple/white)
F - Convenience Center - A (grey)
G - Switch Illumination wire fed from fuse 12 (pink)
H - F16 (light blue)

C2 (white) to TCCM

A - F14 (green/black)
B - E4 (green/black)
C - F1 (purple/white)
D - F2 (tan/black)

I checked resistance on the switch - good
I checked continuity on each connection - good
I checked New AC Delco encoder motor and 3 junkyard encoder motors. From 236 and 246
I checked four junkyard TCCM’s…from 236 and 246…one from 246 worked til it didn’t.

Snowgeek seems to have made this switch work, but I have thus far, failed…Next I’ll try wiring the same switch racrx7 used with 236 encoder and 236 TCCM, I guess. It made the choice to use the encoder and module from the model that used my switch, but maybe that was the mistake?

But why would it work at all, if that’s the case?

Currently, only the red Neutral light illuminates when I turn the key and/or start it. Service AWD comes on and shuts of which each turn of the key.

Any ideas? Pretty please? Haha

You folks are awesome, either way.

[AstroSurf]

I think I figured out my mistake when I was gearing up to change the switch to the type Rinny used that’s wired like the one racrx7 used...

I think this:
G - Switch Illumination wire fed from fuse 12

is supposed to be fed from fuse 15!

Will update when I’m able to test, and will confirm wiring the vertically oriented switch with various motors and TCCM’s, hopefully. (will post photos once I inform myself how)

[AstroSurf]

So...That didn’t work, but I can now hear signals being sent to the TCCM when I push buttons on the switch.

I used a fuse tap at fuse 15 under the dash instead splicing into E10 a second time. (1st time for relay) Would that cause any issues?

Another quesrion...could a shop with a scanner read this grafted 4wd system properly? Or, no, cuz the protocols, etc...?

[AstroSurf]

Alright…so I wired in a switch from a 99- Blazer that has the same blue plugs that the switch racrx7 used.

Lights all came on, and 2Hi was lit.
Auto AWD stayed lit.
No 4Hi
But, when I push Auto AWD, and the trans is in Neutral, it switches to 4LO and back out when I push AWD, again.

I wired it just like the instructions. Tested continuity, etc.

I ordered a switch from a 99 suburban, like racrx7, if that doesn’t work, I’m just putting the old encoder and TCCM back in. I’m about to give up.

[AstroSurf]

It was the switch!!!

I didn’t test resistance at Nuetral on the switch I tested, and molded i to my dash pre-maturely. (holding 2Hi and 4Lo) That’s why I couldn’t find the hiccup.

I was aboit to pull my hair out. I was questioning whether I made the right choice to use a 236 instead of a 233, but now that’s it’s done, I’m glad I did it this way.

Anyway, please feel free to reach out with questions if anyone else is thinking about this mod. I have all the parts to turn a 136 into a 236 plus a pile of electrical parts. Thinking about making a kit for someone.

Thank you Captn Crunch! You got this started almost a decade ago, it seems. And, racrx7, of course. And SnowGeek and his Google Doc, and every poster on this thread. Herbie, too, up there.

(Not sure about WoodButcher, yet. Hahaha! Only kidding!)

[tanvanmanwithaplan]

We're online!!!!!

Switch operation:



Transfer case testing.



2hi still spins the front axle unless I lightly brake I think this is normal from clutch plate preload. I'm pretty stoked. I have no fluid leaks yet. I was able to get a pretty clean looking 78k miles 236 for $200 in St. Louis and no funny noises yet. Only light alley and yard testing so far. I lost a lug stud a few weeks ago so I don't want to go too crazy until I fix that.

Thanks captn' crunch and racr7x.

I'll probably post another video once I get my 4lo done. I also have a saved instagram story of each step of the process I might put together into another YT video like a slideshow.

[AstroSurf]

Nice work!!!

[AstroSurf]

Thanks captn' crunch and racr7x.

I'll probably post another video once I get my 4lo done.

I can help with with connecting to the ECM, if you need it, but not sure what year you have.

I drilled a small hole in the firewall behind the battery…3/32 bit, I think.
Then,I shrinked wrapped the section of line that runs through the engine bay with 1/8” wrap, and sent the shrink wrap through the hole in the firewall to make an airtight seal.
Then, I ran 1/4” loom over that back to the firwall.

You have to remove the battery, but then you have a chance to clean and paint your batttery tray.