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Seat upgrade problems in 03 TB

8K views 20 replies 6 participants last post by  thecrave 
#1 · (Edited)
I'm rebuilding an 03 TB, and I came across some better seats, but I'm having some problems getting it working. Any help would be appreciated.

Stock, the truck had leather seats with power adjustment (only).

I replaced them with leather power and heat (and possibly memory). I swapped out the door switch module with one that supported the heat and memory (1/2) buttons (the 1/2 seat buttons are around the door lock/handle, the heat is on the lock switch).

Problem is, there seems to be no power to the new seats. They don't move (driver or passenger) and the heat buttons don't work.

The memory buttons make a "ding" when I press them, but nothing happens.

The module under the driver's seat is p/n 15091593.

I tried replacing it with a module I got on eBay, p/n 15206270.

Neither worked.

If I put my old seats back in, they work (power adjustment). But there's no "module" for them -- so I know I have power to the seat wiring harness.

I've swapped the "seats" fuse/relay in the 2nd row fuse box, and checked the DCM fuses. All seem good.

Do I have to "program" anything (BCM) to show that I have the new module?

Could I have a bad module? Or two bad modules? Is there any way to diagnose it myself?

OR, is there a relay/fuse that I'm missing that's specific to the heat/memory seats?

Thanks!
 
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#2 ·
did you try swapping the modules with your old seats ?

also clean up your mailbox, i tried sending you an pm, but it was full

if you still have your old seats and want to sell them...i'm interested
 
#3 ·
I did try swapping the modules under the drivers seat and that didn't work, but just read last night that there's a TSB for 02 that the modules lock-up and need to be replaced.

What was interesting is the fact that the TSB points out there's 2 modules per truck if you have heated seats. I only looked under the driver's side.

I'm not near the truck today, so I'll have to try and swap out the second module (assuming it's under the passenger seat).

I couldn't find anything online about the module under the driver's seat is p/n 15091593, but I did find the module I got on eBay, p/n 15206270, listed as the replacement part in the TSB.

PM's cleared up now, thanks.
 
#4 ·
OK, I tried swapping the module under the passenger seat, and no change.

No response from either seat while they are in place. Heat or power movement.

I still hear a chime from the dash speaker when I press 1 or 2 on the seat memory selector and see a response on the DIC.

But nothing from the seats themselves.

Does the BCM, or the seat module, need to be re-programed to accept the upgrade/swap?


I hope to have it on a Tech 2 later this week to see if there's communication with the modules, but don't have a wiring diagram to determine if it's something I'm missing (fuse/relay/link, etc).


Any thoughts would be appreciated.
 
#9 ·
harness is identical, it plugs into the floor of the truck just fine. same number of wires and same position.

i'm thinking it's the module. just not sure if it needs to "learn the VIN," be reprogrammed or if the module is locked up (as per TSB)

Is there anyone out there that knows more about this module, or diagnosed it with a Tech 2 before?

I'd just hate to buy two new modules ($200 ea) and that not be the problem and be stuck with them. Not easy to unload. (unless anyone knows a parts place w/ a good return policy)
 
#12 ·
Yup. The truck is being rebuilt, and every night after I leave the shop, I disconnect the battery (since I've had it run down on me if I don't).

A friend has ALLDATA and I read on there that the Tech 2 can "talk" to the modules. It didn't say anything about re-programming them, but maybe there's a code or clue that the Tech 2 can give me.

Just trying to avoid that stage, since it means going to the dealer and shelling out some dough! ;-)
 
#13 ·
I think I have my best clue yet.

I have the right RPO code for keyless entry, but I can't program any remotes (I have 4 I've tried, all with the right p/n).

So I'm thinking it's the LGM, Liftgate Module.

But the LGM, being part of the liftgate that was factory to the truck was never replaced. Neither was the BCM.

So RKE and Memory/heated/power seats don't work.

Could it be that the LGM went bad while the truck sat in storage or was being worked on? Are there any other components that are part of the LGM that I could use to "diagnose" the problem as being definitively the LGM as the reason for both problems?

I've already confirmed that the license plate light works (as per some diagnosing), so the ground must be good. But I don't have any mass codes or freak-outs in the vehicle. What else is controlled by the LGM?

Stinks that I'm really in a corner here, needing a Tech 2.... just want to make sure.
 
#14 ·
I continue to update my progress here, for posterity. :)

Turns out that when I replaced the back-seat fuse block from a newer model truck, there isn't a connector going up to the LGM fuse from the wiring harness (square block connector) below (must be a different layout).

If I put a small drill bit in the right side of the fuse socket to reach all the way down to the wiring harness below, and use a small wire to connect the drill bit to the left side of the fuse block (where there is 12V, I get power to the LGM. So THAT issue was getting power to the LGM.

Meaning the wiper works, the keyless entry works, the gate lock works. Normal, expected LGM behavior.

But the seats STILL don't work. grrr...

Does the LGM need to be programmed to work with memory/heated seats, since it didn't originally come with that RPO?

The investigation continues....
 
#15 ·
While the LGM is the interface for the RKE, I don't believe it controls the seat motion or heater, that is done between the BCM and individual door modules. (The door modules also control the memory mirrors). A Tech-2 is used to program and talk to pretty much every module in our trucks. Be careful, if you blow out a door module, you loose all controls on that door, including mirror, seat heat, locks, windows......the dealer blew one of mine reprogramming it a while back. I *think* the power seats still worked manually, just with no memory or auto-exit feature. (Mirror on that side didn't work at all, including the dimming feature - one way to tell if the module is toast).

Is there any power on the harness going to the seat? - I know they don't work, but is the harness live? I know there have been a members who have installed LT seats for an LS and the seats worked. GM has changed the seats a couple of times, the '02 models have side air-bags standard (at least the GMC did) and have dual lumbar (4-way switch). In '03 they changed to a single lumbar and I believe the side bags became optional. In '04 or '05 they made some additional changes to the seats themselves, which might help narrow down what year seats you have. - Also keep in mind that I believe the SB2 (serial bus) was slightly changed between '02 & '03, along with the Onstar interface. (Onstar was again changed in '04 or '05). I mention the Onstar change, as those are the circuits that talk to the airbag module(s) to determine if they're ready or have deployed.
 
#16 ·
Very cool info.

There IS power in the harness going to the seat, but the seats won't move, nor does the door module switch for heat light up. I can put the original seats in the truck (power only) and they move just fine. I'll bet if I found the right harness going into the seat module and plugged it directly into the floor harness, the seat would move (bypassing the seat module).

The mirrors move just fine, window controls, lock controls -- they all work on both sides. Even the memory button makes a "ding" when I press the 1 or 2 switch.

The upgraded seats have airbags (not the originals), but I didn't plug that harness in. I don't want to trip an airbag code (or worse) if there's a mismatch.

Both sets of seats have a sliding horizontal --- control, a vertical | control and a circular 4-way <-^-> control. On the original seats the 4-way control is big and mostly smooth, where the replacement seats control is smaller and the "direction" indicators are more defined (if that makes any sense).

I didn't check earlier, but I'm wondering if the harness wires changed at all. I'll see if I can dig up a diagram.

Let me know if the above descriptions mean anything to you -- compatibility-wise.

Thanks!
 
#17 ·
The original seats with the smooth 4-way are single lumbar, the replacement seats with four arrows up/dn/front/back would be from a 2002 model year vehicle. That's the only year that had both lumbar adjustments, where forward/back arrows control one bladder and the up/down control the second. - On the original seats, only two of the positions on that button or switch should do anything.
 
#19 · (Edited)
Might need a Tech-2 at this point, on the wiring diagram, there's a brown wire going from the switch assembly on the driver's door module to the memory seat module and a tan wire from the passenger's door module to the passenger memory seat module. (I didn't know there's a memory module on the passenger side, but apparently there is). They specifically show it split to feed both the normal destination and the memory seat module (when so equipped), however I don't have any schematics for the memory seat modules. - Only shows the two wires, one for each seat and that those wires are listed as Class-2 Databus on the wiring diagram.

I downloaded the diagram either directly off of TrailVoy.com or a posting by a member back on July 7th, if you want a copy of the diagrams.

Scratch Part about resources section, those are only the ignition circuits for wiring an alarm.....not what I'm looking at. Just downloaded the '03 & '02 for comparison and its not what I have. If any of the mods would like a copy of the wiring schematics for posting, please let me know and I'll e-mail it to them. (Unless the original poster already has).
 
#20 ·
#21 · (Edited)
Very cool ylab!

I was able to determine that there was no power in the second orange wire going to the seats. The smaller one.

I traced that back (again) to the rear-seat fuse block. The wire was there, but not "connected" to the block above, or a fuse (same with my LGM problem, since it's the same fuse). Some handy-work fixed this, and now I have power and heated seats!!!

Yeah!!!!


BUT -- it looks like the memory functions don't work. The buttons beep, and the DIC recognizes the remote/driver, but the learning function isn't working.

I'm guessing at this point that it's probably a BCM issue and needs to have the RPO code (AAB) added for the memory feature, since it wasn't original to the truck.

At least I know everything's got power (and found out I need to replace the front up/down motor on the driver's side).


Thanks for the help ylab!
 
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