Instrument Cluster Changes '99-'04

[The_Maniac]

I just added a reset button to the '04 and it works. I just had to tie a momentary contact button to pin A12 on the middle (large/24-pin gray) connector on the BCM. I did not route the BCM wire or ground through the fuse block (at least not now, maybe later). I grabbed a reset fuse panel button from the junk yard and made a pig tail hanging in the fuse panel.

Now, something I found of interest, that button is also used to reset the tire monitor. If you use it to make the change oil light on the dash blink, the next push/release of the reset button should go to the tire pressure light, then push/hold resets the tire monitor (and should chime, like the oil life monitor reset). I get no chimes, but if you follow the button pushes cycling through the two different resets, the car responds like it's doing the tire pressure reset (just no chirp).

So, I'm wondering based on that, perhaps the tire pressure monitor is still there, GM just programed the audible response out of the BCM and made a change to the cluster. I'm going to see if I can find a '99 cluster with RPO code UJ6. If I do, I can first test how the tire pressure light works in an '04 with the reset button (does it visually do a reset). If so, then I want to compare the boards for missing components on the '04.

This is purely me being curious at this point. If it works, sweet, if not, hey, I got my cruise light and that was the big one (and I now have a reset button for the oil life ).

[plastic_indian]

Kudos for putting this much effort in documenting vestigial features!

[HOYS]

I like when GAGT talks tech and not trash.

[Pontiac_guy99]

I hope one day I will have an oil level indicator or tire pressure sensor. I am really nervous about changing anything on my car though... That's why it's almost completely stock. Any changes I do are done with a mechanic relative.

But that's a great effort you put forth into this project.

[The_Maniac]

If I did not have the want to change the oil pan, I would probably do an oil level indicator. There is a wire near the oil pan on my car that is for the oil level switch (but the pan does not have have the holes for it and I'm not drilling the pan). After that, you would probably need to add the missing components to main board of the cluster to add the light (I have not tested it, nor will I mess with it).

I hope after my next junk yard run that I might have a cluster to get more information from for the tire monitor.

[pauljs75]

Interesting thread... I noticed the instrument panel in Grand Ams do a POST (power on self test) of sorts, I like that feature because it lets you know all your lights and guages work as they should. Any that don't are burnt out or have problems. Shouldn't you be able to monitor the BCM and tell what signals are available from it to the instrument panel within the first three seconds of key on? Just something to keep in mind.

[The_Maniac]

Paulis75, it's not as easy as just turn the key, check what lights pop up and go from there. GM did away with some of these indicators, so I can't power on the cluster and do a simple check if the lights work, as the cluster is missing components from it. So one part is hardware missing and the second part is hoping the software is still n the various parts of the computer systems (the cluster and BCM) to drive the features.
In the case of the cruise light, I just needed a resistor and a LED.

Right now, I am waiting to come across a cluster in the junk yard for a Grand Am with RPO code UJ6 (this is the RPO code that the car has the tire pressure monitor). If I can get one, then I could try a couple of things.
- I can power it up on a bench and see if all lights do a test. When 12v power is applied to the ignition line, the lights all cycle (so this actually does not tell you if the BCM has the programming in it).
- Next I can plug it into my car and run through the reset for the tire pressure system (now that I have the reset button wired into the car that GM got rid of in the '04 model).
- If the tire pressure light functions with the reset, then I assume that the visual part of the system is still in the software, but any audible part is deactivated (which for what I'm playing with, I'm fine with that).
- If all this so far looks promising, compare the clusters and see what components I need to complete my '04 cluster that the UJ6 one has and I don't. I'd simply use the UJ6 cluster, but I want my mileage to be accurate. So my last and final hope on this part of the game is that the logic for the tire pressure system is still in any of the controller chips for the cluster (and that the components of the system is what GM did away with).

It's a trial and error experiment, in hopes of seeing what can be done to restore functions GM did away with. And if I can't bring back the tire pressure system, oh well, it was neat to play with. I'm just thrilled to restore the cruise light GM did away with.

[TriumphoverU]

Originally Posted by The_Maniac

- If all this so far looks promising, compare the clusters and see what components I need to complete my '04 cluster that the UJ6 one has and I don't. I'd simply use the UJ6 cluster, but I want my mileage to be accurate. So my last and final hope on this part of the game is that the logic for the tire pressure system is still in any of the controller chips for the cluster (and that the components of the system is what GM did away with).

Correct me if I am wrong, but I do not believe the Mileage is stored on the main circuit board, I believe it is stored on the secondary circuit board that is attached to the odometer display. Therefore you should be able to swap main boards and still retain your original mileage.

[The_Maniac]

Already tested that.

I have access to a 2000 cluster that unfortunately does not have the tire pressure monitoring, I pulled the main board and put it into my cluster (so I would be using the display board that belongs to my '04). When I plugged it in and powered it on, the mileage displayed belonged to the '00 not my '04.
The mileage is either stored on a chip in the main board OR on the secondary board that is hard wired to the main board. It is not in the board that works the display.

That would have been great if it was, making this concept very easy (just a board swap).

[TriumphoverU]

Appreciate the info, I happen to have a board with the cruise light and the tpms light, and was going to try installing it, but like you, I would like to retain my original mileage.

I believe the board I have may be missing one component right next to the tpms light. If you look closely to the right of the LED you can see there appears to be a spot for an electronic component. Not sure if that component is not needed or if the TPMS does not actually work on my board. I find it funny that GM would waste the money to put the LED on the board, but not install the next component for 1 more penny. But I also do not have the switch or any other components wired into my car to try it out.

[The_Maniac]

Interesting, do you know that board came from a car that had the TPMS system (RPO code UJ6)? The reason I ask, the 2000 Grand Am GT I did the mileage test with, it has an LED in the spot of the TPMS system, but in the power on test, it never lights up (and owner's manual makes no mention to that 2000 Grand Am having TPMS, but according to the '99 owner's manual, the light is supposed to cycle on with the rest of the lights.

From my goofing with these clusters, you can power on test the board without it being in a car (a simple 12v power supply works, I have been using a power supply for a hard drive USB adapter to test mine).

The missing component (marked C46) next ot the TPMS light, I believe based on the labeling GM used is a capacitor. But I'm not sure if it's required for the TPMS or just happens to be there. My father and I wired in an LED and a resistor in the pathway of the TPMS light (no other components were missing in the pathway from an IC to the light) and it never power on tested. I'm suspecting other components are missing to activate that pathway.

Also, something I find funny, I think it's the air bag light (lowest light to the far left), notice GM had a space for a 2nd LED. Wonder what for???

[TriumphoverU]

I don't know if it came with the tpms or not, it was an ebay purchase, that I needed for the stepper motors. Which pins are power and ground, and I'll check to see if it works or not?

[The_Maniac]

Pin 6 is ground and you will need to apply 12v to pins 4 and 8. That will be enough to have the cluster do a quick power on test.

[The_Maniac]

I still don't know if the Tire Inflation Monitor can be resurrected, but I accidentally stumbled upon something about this in the shop book that I thought I might share.

It claims all the software for the TIM system is stored in the EBCM (Electronic Bracke Control Module).

When the EBCM detects a low tire pressure condition, the EBCM sends a message to the instrument cluster via the serial data line. The instrument cluster displays the warning message LOW TIRE PRESSURE when commanded by the EBCM, via the serial data line.

I also looked up, swapping the EBCM is plug and play (no programming required). You just need an EBCM for a car with or without variable effort steering (and I am not sure how to tell if a car has it or not).

So, what I suspect now:
- a light (and probably a resistor) need added to the cluster (probably just like what the cruise required).
- EBCM needs changed out (which that expands my search, I can pull one from any Grand Am or Alero that had the UJ6 option code.

I may take a moment to mess with the cluster and add the LED, trace the route and see if a resistor is needed and for giggles see if the reset button works for the TIM system (working off the idea that maybe there really is no change in the EBCM or it's just part of the process to figuring this out).

[AaronGTR]

That makes sense, since the system doesn't have actual pressure sensors in the wheels like newer cars, and just works based off reading differences in the individual wheel speeds. And the EBCM controls the TC and ABS systems based off the wheel speed sensors.

It's pretty easy to tell if a donor car has the variable effort steering or not if you can look at the engine. Variable effort cars have a wire harness lead plugged into the bottom of the power steering pump, for the electronic control solenoid. Non-variable effort cars have no plug on the pump and no lead for it on the harness.

It's an interesting project just based on the process of seeing if it would work or not. I wouldn't see much point in having it though. I had a similar system on my '97 GP, and it never worked very well or was very accurate. I think it worked one time when I got a nail in a tire and it was actually low. Every other time it went off was a false alarm.

It would be interesting to see if someone could add the variable steering assist to a non-variable car. That would actually be more useful I think.

[The_Maniac]

Thanks Aaron for the variable steering info!! You don't happen to have the RPO code that would be associated to it, would you?
I don't think my '04 has variable assist (the steering on it feels stiffer than my '02 did and any other Grand Am of this generation I've driven). I'm sure variable effort could be retrofitted. Obviously I now know the EBCM plays into (without checking the shop book, my guess is the EBCM connects to a variable effort PS pump).

As for the TIM system, I've dealt with it on my '04 Monte. Because it doesn't use pressure sensing valve stems, as you pointed out, it's not as accurate. Even though GM states it doesn't really detect until about 12lbs low, on my Monte, it went off for being 5lbs low.

Just Friday I had a tire go flat while I was on the road (driving did not feel off, it just sounded like a lot of snow in a wheel, but the sound prompted an immediate pull over and inspect). Was an annoying day for a wheel problem. Not sure if the TIM system would have had a chance to assist or not (that's a gamble).

Admittedly, I'm more interested in seeing if it can be done for the sake of doing it (and if I can, I have a feature GM did away with)

[rocketfast123]

And it doesn't help if all your tires are low. My 01 Alero has it, and yes it works well for me, it kicked on at about 10psi lower than the rest.

[The_Maniac]

An '01 Alero has it? I wonder if GM kept it in the Alero line but dropped it in the Grand Ams? Anyone have any info on that?

And I think I understand the logic to it not going off if all tires change in pressure, it's to account for natural changes from tires going from hot/cold (since again, it's basing it off a change in wheel rotation, not actual pressure).

[The_Maniac]

OH, and I found the RPO code for variable effort steering, it's NV7.

[plastic_indian]

NV7 is VES; N40 is non-variable.

The system is relatively simple; the EBCM takes inputs from VSS and steering angle sensor (SAS on the bottom of the column) and outputs a PWM signal to solenoid/pintle (the EVO - Electronic Variable Orifice) on the pump; full flow is the normal state for the pintle.

GM support of the VES setup is fading (or already gone?). The EVO actuator is no longer available for (at least some) light trucks (several personal experiences with G vans); an elimination parts kit (effectively a bypass) is now available.

Delco lists two distinct part numbers for the '02 LA1 N car EBCM (12231871 w/NV7, 18078142 without); whether this reflects a hardware variance or simply the software loaded (since the EBCM is supposed to by plug-n-play on this application) I cannot guess. It may be worthwhile to input a known N40 VIN into TIS2WEB and see if NV7 and N40 calibrations are both available for the EBCM.