Added trans temp to cluster and replaced bulbs with LEDs

[Tonimus]

Been wanting to add a trans temp gauge to my cluster for a long time. Also had a bulb die behind the speedo. Didn't want to send it out for $300 worth of service when I had everything I needed but parts.



I picked up a new LED series face on eBay from GM Gauge Repair. Ordered LEDs from another seller, and a 2006 Trailblazer cluster for $30 shipped.

Scavenged the steppers, needles, and cluster pigtail from the Trailblazer cluster and scrapped the rest.

Before I started.


LEDs soldered in.


Reinstalled in the Tahoe.


I was able to use my OBDX Pro VX and the pigtail from the Trailblazer cluster to make a little bench harness to program and test the cluster. On the gauge plug, pins A12 and B12 are ground, A11, B9 and B11 are +12V, and A6 is serial data. OBD2 pinout is Pin 4 and or 5 are +12V, pin 16 is ground, and and pin 2 is J1850 serial data. Hooked all that up to my laptop with IPC Hammer to turn on the trans gauge.

All is good. I should've been slightly more careful in putting the needles back on, but I compared it to live data from the OBD2 port and I just need to adjust a tiny little bit. Easy enough to fix and it was caused by my lack of experience doing this. All in all, pretty good for my first GMT800 cluster.

I know none of this is new and people have been doing this for ages. But this was pretty easy and if you're handy with the soldering iron, not at all a problem.

 

[stutaeng]

Very cool!

It's kinda crazy thinking that the data for the transmission temperature has always been there and the ECU has it, just only displayed on the cluster on certain models, no?

I believe the manual transmission trucks never came with the transmission temp guage on the clusters, even the HDs/Duramax models (?)

 

[ORVietVet]

The transmission temp gauge pigtail plug in is right there behind cluster. The 1500HD series and bigger had the transmission temp gauges.

 

[Tonimus]

Very cool!

It's kinda crazy thinking that the data for the transmission temperature has always been there and the ECU has it, just only displayed on the cluster on certain models, no?

I believe the manual transmission trucks never came with the transmission temp guage on the clusters, even the HDs/Duramax models (?)

This is correct. My understanding is 2000-2002 and some 2003 clusters all have the programming for temp, you just need to physically install the gauge.

In the later ones, it's just install and click a button in software.

The transmission temp gauge pigtail plug in is right there behind cluster. The 1500HD series and bigger had the transmission temp gauges.

Which models is that for? My Tahoe needed nothing extra plugged in.


Slowly working my way through the rest of the burn out or dim bulbs.

 

[ORVietVet]

Which models is that for? My Tahoe needed nothing extra plugged in.

As far as I can remember, the 2003 thru 2006 GMT800 regular 1500 series dash cluster harnesses had the pigtail, just sitting there, behind the cluster. Waiting to be plugged in to the clusters that did have the transmission temp gauges.

 

[Tonimus]

Ah. There's no extra pigtail. The data is carried on the same wire as the other serial data. All 2003-2006 GMT800 clusters (and 2007 classic) have the same pinout on the only connector on the back. 2000-2002 have a different pinout, and I don't know what else may be different.

 

[ORVietVet]

At 73 years old and the time I dealt with the cluster being about 3 years ago, I just can't remember for sure. As best I can remember, there was a whole other pigtail I plugged in BUT, I could be completely wrong. If I am, I am sorry. I do remember that there was no "running another harness" issue to be dealt with. The connection(s) were right there.

 

[Tonimus]

Just have the front and rear HVAC controls left to do. My upper steering wheel controls remain unlit because I didn't want the $100 module for the radio when I prefer to reach over.

 

[stutaeng]

Looking good!

Looks like you did some of the steering wheel control buttons? I need to replace those on my 06? Where did you buy those?

 

[Tonimus]

Looking good!

Looks like you did some of the steering wheel control buttons? I need to replace those on my 06? Where did you buy those?

I did the bottom controls for the DIC. They are a pain in the behind. I popped them open and unsoldered the bulbs, soldered LEDs back in.

There's nothing to them. If yours don't work, it's more likely to be the clock spring than the buttons themselves.

 

[stutaeng]

I did the bottom controls for the DIC. They are a pain in the behind. I popped them open and unsoldered the bulbs, soldered LEDs back in.

There's nothing to them. If yours don't work, it's more likely to be the clock spring than the buttons themselves.

Oh, darn.

Yes, the buttons do work, but some of the bulbs are burnt out. I did the cluster LED upgrade and the HVAC LED upgrade as well. I can't remember where I bought the kits, ebay maybe? It was like 4 or 5 years ago?

 

[Tonimus]

Oh, darn.

Yes, the buttons do work, but some of the bulbs are burnt out. I did the cluster LED upgrade and the HVAC LED upgrade as well. I can't remember where I bought the kits, ebay maybe? It was like 4 or 5 years ago?

The hard part is digging out the buttons and then reconnecting them. I would suggest popping the airbag out, and using a curved tool to push the switch out from the back side. It'll make sense with the airbag out.

I used 3mm diffuse 12v LEDs. You can get them anywhere on eBay and such.

 

[Tonimus]

So I did not know that the AC controls are all ABS. And my truck sees A LOT of UV exposure. Talk about brittle. Ended up destroying the passenger side temp slider trying to get the knob off. Lost two clips on the rear controls and had to use 3M tape to keep it mounted. Oh well. Looks good, though.

 

[JorgeS]

Maybe I misunderstood... were you able to retain the correct odometer reading?

 

[j_dizzle68]

Been wanting to add a trans temp gauge to my cluster for a long time. Also had a bulb die behind the speedo. Didn't want to send it out for $300 worth of service when I had everything I needed but parts.



I picked up a new LED series face on eBay from GM Gauge Repair. Ordered LEDs from another seller, and a 2006 Trailblazer cluster for $30 shipped.

Scavenged the steppers, needles, and cluster pigtail from the Trailblazer cluster and scrapped the rest.

Before I started.


LEDs soldered in.


Reinstalled in the Tahoe.


I was able to use my OBDX Pro VX and the pigtail from the Trailblazer cluster to make a little bench harness to program and test the cluster. On the gauge plug, pins A12 and B12 are ground, A11, B9 and B11 are +12V, and A6 is serial data. OBD2 pinout is Pin 4 and or 5 are +12V, pin 16 is ground, and and pin 2 is J1850 serial data. Hooked all that up to my laptop with IPC Hammer to turn on the trans gauge.

All is good. I should've been slightly more careful in putting the needles back on, but I compared it to live data from the OBD2 port and I just need to adjust a tiny little bit. Easy enough to fix and it was caused by my lack of experience doing this. All in all, pretty good for my first GMT800 cluster.

I know none of this is new and people have been doing this for ages. But this was pretty easy and if you're handy with the soldering iron, not at all a problem.

I've been wanting to do cluster LED's but at night I dim my cluster down real low. I keep asking people on TikTok if the LED's will dim but I never get an answer.....

 

[Tonimus]

I've been wanting to do cluster LED's but at night I dim my cluster down real low. I keep asking people on TikTok if the LED's will dim but I never get an answer.....

They do. Not a ton of range, but sufficient.

 

[Tonimus]

Maybe I misunderstood... were you able to retain the correct odometer reading?

Yes, and with the tools I use, it is shockingly simple to correct the reading. If I had to replace the whole cluster rather than modify my own, I would have had to correct the reading.

 

[AuroraGirl]

what all can IPC hammer do?

 

[Tonimus]

what all can IPC hammer do?

It cannot do engine hours, I don't think. My cluster reset that on its own sometime since I bought it. It can do odometer correction, stepper motor calibration, basic function check, and add trans temp. You can also do a custom startup message, but I haven't played with that at all. Since the cluster is connected directly to the data network, you can also do all of the functions in the vehicle. It's pretty neat stuff. If there's something specific you want to know if it can do, feel free to ask and I'll see if I can get it to do it. I'm still new to it and learning.