06 TB LS gage cluster, burnt out lights and calibration

dmtaurus

Original poster
Member
Jul 1, 2012
42
I had the dreaded burned out light problem at several places on my gage cluster. To replace the bulbs the cluster has to be removed from the dash, the clear lens taken off, the gage needles removed from the stepper motors using a regular table fork, remove the gage markings plate, before you get to the bulbs. Then, you find out that the bulbs are soldered to the PC board. So, I unsoldered the bad bulbs and replaced them with bulbs from Radio Shack. That worked ok but later I found out that the RS bulbs are not quite as bright as the originals, but oh well. (I didn't find the better bulbs till I did a search and found cluster rebuilders that sell the same brilliance of bulb. I'll buy them instead if I have to replace others.)

Anyway, I took note of the needle positions and match marked the needles to a piece of painters tape applied to the gage markings plate. After replacing the bulbs I aligned the needles with the match marks as best I could. A later test drive revealed that the speedometer showed that the speed is 2 mph too slow, using GPS as a standard. Looking into the subject of calibration, I found and bought a used Kent-Moore J33431-B signal generator that will calibrate all the gages in the cluster. It came with usage directions but they are kinda sketchy. I downloaded Mooseman's service guides, and the guide on 02~05 TB's, section "Gages", is really helpful. It takes a little hunting to identify connectors 1 and 2 on the PCM but with lots of cross-referencing between the guides, it can be done and the various gage wires identified.

The problem is I want to be sure I set the switches on the signal generator correctly before applying a signal to the speedometer circuit (I don't want to fry the electronics on the PC board) so that I can reset the needle positions. I know this is a rather technical question on the electrical side of things but if anyone knows how to properly set-up the generator, and with what Kent Moore wire harness connectors to use, please let me know. Kent Moore's website, gmspecialservicetools.spx.com, has the generator but lacks instructions on how to use it. I figured anyone with direct experience would know best. Thanks.
 

Blckshdw

Moderator
Nov 20, 2011
10,654
Tampa Bay Area, FL
I couldn't find that device on their site (very quickly) although I'm not really awake yet. :yawn:

Most of us who have tinkered with our clusters (I believe) have an OBDII reader such as a Scangauge II or an Android phone with the Torque app and a bluetooth adapter, so we can read real time data. The easy way to go, is half assemble the cluster when you're done, leaving the clear lens off. Drive around the block, and compare what the needles say, to your OBDII reader. This is mainly for the tach, speedometer and voltage.

For any needles that are off, make adjustments to the needle placement, test them until you're satisfied, then finish assembling the cluster. Nice and easy. :thumbsup:

Edit: This is also a perfect opportunity for you to upgrade your lights to LEDs!! :yes: :biggrin:
 

BRomanJr

Member
Dec 9, 2011
371
dmtaurus said:
I had the dreaded burned out light problem at several places on my gage cluster. To replace the bulbs the cluster has to be removed from the dash, the clear lens taken off, the gage needles removed from the stepper motors using a regular table fork, remove the gage markings plate, before you get to the bulbs. Then, you find out that the bulbs are soldered to the PC board. So, I unsoldered the bad bulbs and replaced them with bulbs from Radio Shack. That worked ok but later I found out that the RS bulbs are not quite as bright as the originals, but oh well. (I didn't find the better bulbs till I did a search and found cluster rebuilders that sell the same brilliance of bulb. I'll buy them instead if I have to replace others.)

Anyway, I took note of the needle positions and match marked the needles to a piece of painters tape applied to the gage markings plate. After replacing the bulbs I aligned the needles with the match marks as best I could. A later test drive revealed that the speedometer showed that the speed is 2 mph too slow, using GPS as a standard. Looking into the subject of calibration, I found and bought a used Kent-Moore J33431-B signal generator that will calibrate all the gages in the cluster. It came with usage directions but they are kinda sketchy. I downloaded Mooseman's service guides, and the guide on 02~05 TB's, section "Gages", is really helpful. It takes a little hunting to identify connectors 1 and 2 on the PCM but with lots of cross-referencing between the guides, it can be done and the various gage wires identified.

The problem is I want to be sure I set the switches on the signal generator correctly before applying a signal to the speedometer circuit (I don't want to fry the electronics on the PC board) so that I can reset the needle positions. I know this is a rather technical question on the electrical side of things but if anyone knows how to properly set-up the generator, and with what Kent Moore wire harness connectors to use, please let me know. Kent Moore's website, gmspecialservicetools.spx.com, has the generator but lacks instructions on how to use it. I figured anyone with direct experience would know best. Thanks.

The gauges will never be perfectly accurate. You didn't mention that you had checked calibration before you disassembled the cluster so the speedo could have been off before you started.

In my experience, there are two ways to get the gauges most accurate:
With the clear lens removed and plugged into the wiring, Turn the key to run, don't start, then turn off the key. Any gauge that is not on zero should have the needle removed, cycle the key again to re-zero, the carefully press the needle on at zero.

Another way is to note the amount the needle is off and turn the gauge manually in the direction of zero with the needle on it past the zero point until it goes to end of travel, then force it to turn past that point the same amount it is off (you should feel the needle slip on the shaft). Then recycle the key and check for zero once key is off.

If any gauge fails to return to the same spot after each of 2 or 3 key cycles, the Stepper Motor is bad.
 

dmtaurus

Original poster
Member
Jul 1, 2012
42
One other reason for doing this, that I forgot to mention, was to install the GM gage lens that has silver circles, which does look really good.

I did check the speedometer with the GPS before doing all this and it was dead on with the GPS. Whoever did the gage cluster settings really did a good job. The signal generator mimics the signals that the sensors send to the PCM. I guess that is why I chose to try that route; it was $70.00 for the tester and came with some wire harnesses as opposed to a new one which costs over $800.00.
 

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