What TCCM's are compatible with each other?
 

I have a 98 Bravada. I bought a replacement ac delco 19326776 TCCM. That is listed for my year, but ALSO listed is ac delco 19326778, which has a foot note about having an NP1 transfer case.

The AC delco didn't fix the problem. It won't even illuminate the "service AWD" light. So I went to the junkyard and found two modules from blazers. One is a 15040103 and a 15154323

I put in the 15154323 and it illuminates the light, but doesn't work. I also have an orange connector yet there are pics all over of green connectors and mention of an NP4 transfer case. To my knowledge, they only came with NP-136 transfer cases.

So is there a difference between them all? None of the cross reference charts mention anything other than year. 98-01

When trying to figure out such things, I'll look at the OE part numbers for different models as listed in a GM parts website such as https://www.gmpartsxperts.com/ so I can cross-reference them.

In 1999 the Bravadas came with the NVG 136-NP4 transfer cases and the Blazers came with either the NVG 233-NP1 (3 button) or NVG 236-NP8 (4-button) transfer cases.

Yeah I lose all faith in those parts indexes when I look at what transfer case for a 1998 bravada.. and it's part no.GM (24228412)

Which some how also fits all the way to the 2004 Blazer... Does GM even KNOW that the Bravada version is a 1 speed no shift transfer case??????? There are no BUTTONS GM!!!!

I tried to add a hyperlink but it don't seem to be working out.

Also while looking around... The Bravada shares the Transfer Case with the Astro/Safari Vans., Maybe I need a controller from them and not the Blazers?

I would look into the Van's as well, maybe see what transfer case they have, as they are,some not all,AWD and dont have buttons either.

Thank you for the moral support. I may give that a shot. I'll have more info to report once my scanner get's here.

It's very simple. what is the P/N for your original TCCM?

@LesMyer---The tag fell off and disappeared.. can you believe that?

Ok so i have an update.

Went to the junkyard and happened to get ONE controller from an Astro van. Put it in and everything worked.... except I damaged my new encoder when I was doing some rather extreme testing long before the Astro TCCM was installed. It did engage in testing once, but locked up hard and blew the fuse, Upon removal, I can barely get the coupler to turn on the NEW encoder. I think I fried the motor during one of my initial tests.

The stock encoder tested out fine after removal so I put it back on... and the AWD won't engage. So I was a bit stumped and decided to take it off again and apart. I was wondering if I damaged my one and only Astro TCCM with my fried out Encoder.

I tested this with the rear wheels off the ground. Here is a video of the testing I just did. Turn your audio down if you watch. Is it possible for an encoder to be too weak under load, but work fine when tested like this? I also went under with a wrench and manually worked the TC shift stub while turning the driveline. It locked in just fine without much effort and released just as easy.

View My Video

OK - let's approach it this way. Which RPO code option do you have on the sticker in your glove box? You really have to figure out what transfer case you have.

If it is NP1, then your computer number is 15741322 (missing tag) and it would take a Cardone 73-42100 or Dorman 599-100. This TCCM has a single blue connector.
If it is NP4, then your computer number was 12577420, 15011645, 15037160, 15040319, or 15748801 (missing tag) and it would take a Cardone 73-42105 or Dorman 599-106. This TCCM has two connectors. One black, one green.

those are your choices for 1998 Oldsmobile Bravada.

If the tag on the computer that you are trying to use has a different number (or especially a different color connector), then I think it is not the correct one for your application.

To get an encoder motor to move when not installed (you are not supposed to do this), you have to power the circuit to release the encoder brake + apply the voltage to the motor. Otherwise it should stay locked in place, probably blow fuses, and ultimately get damaged.

My advice is to figure out exactly what you have and stop playing with the used parts from seemingly almost random vehicles and new parts that may be damaged. They are an unnecessary unknown. At this point, just get a TCCM and an encoder motor - but get the right ones and get them either rebuilt or new. Summit Racing has the best prices, and if they don't they will price match with anyone on the Internet. It's going to cost you about $250.

Good luck.

Thanks for your attention to this, but I think your approach is assuming some stuff about these vehicles that is only partially true.

The stock and at one time functioning computer that came out of this Bravada uses an orange and black connector. The 1998 Bravada up to at least 2001, uses a single speed NP136 transfer case. No other option was available. It's quite simple compared to what's in the Blazers and Jimmys. The Blazer and Jimmy also use a computer with orange and black connectors (I've got 2 of them sitting here), but they have a few more circuits compared to the simple Bravada/Astro version. When the Blazer computer goes into self check mode, it will find many faults because a few of the systems are literally missing.

As of right now.. the computer problem is solved. Bravadas DO NOT USE Blazer/Jimmy computers. NO way, NO how even if a web site says they do. I may be in a fight with JC Whitney to get this rebuilt computer I bought sent back for a refund. You see, even on their site it shows the replacement computer as the same one used in a Blazer.

My problem now is that I damaged my new encoder, and my stock one doesn't seem to engage the transfer case when actually mounted. But it tests just fine as shown in the video.

Sorry but I'm assuming nothing, nor am I guessing. I'm going off of Cardone and Dorman application info for 1998 Bravada, which happens to agree 100% with each other. If you have a NP4, then for a 1998 Bravada you need the TCCM with the green and black connector - a Cardone 73-42105 or Dorman 599-106. Did you know that your TCCM has to have programming to match your vehicle? Did you know AFAIK AC Delco TCCMs don't come pre-programmed like the Cardone and Dorman ones (apparently why Cardone and Dorman advertise no programming necessary and have different P/Ns for different vehicles)?

Here's the only guess I am making...….. I am guessing that an AC Delco 19326776 can be used in a NP4 Bravada as well as NP8 Blazers if the programming is right.

One thing I am curious about... why did you put used Blazer TCCMs in your Bravada if you know that they wouldn't work????? (your first post)

Encoder motor for NP4 is Dorman 600-906 / Cardone 48-103 - don't try to test it by plugging it into the wiring harness. Install it before plugging it in.

Good luck and best wishes for a successful repair.