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2000 Seville STS
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8 Posts
Discussion Starter #1
I changed the front heater motor (actually, I was GOING to change the heater motor because it was making a heck of a racket and not blowing as much air as I thought it should, and when I pulled it out, I found what looked like a rat's nest without droppings or the characteristic "rat nest smell", AND a LOT of dirt and even a few rocks!). So, having cleaned everything up and testing the motor by plugging it back in while sitting on the floor, I put it back in. Everything was good, the motor was quiet, had a ton of hot air blowing where it was supposed to. I also had a bad O2 Sensor (Bank 1 Sensor 2), so drove it up on the ramps to get underneath. That's when my ABS, Brake, and Traction Control lights decided it was Christmas and began to shine brightly. Decided to wait on changing the O2 sensor until I can figure out what's going on with the codes I'm now throwing. I didn't touch anything other than the heater stuff (but boy, was everything dusty and dirty under there!). Is there a nest of wires I may have disturbed and accomplished a bad connection while messing with the heater, or is it a supreme coincidence that the ABS/Brakes?Trac Control started at the same time? OR did something break or pinch when I drove it up on the ramps? Any advice or observations would be GREATLY appreciated!
 

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White Diamond '03 DHS (with DTS floor shift)
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Re: 2000 Seville STS P1571, P1644, U1040

Pull the DTC's again. There should be a chassis (C) code pointing to your ABS or TC problem.

P.S.
Be sure to post the code definitions along with the codes. We don't have them all memorized yet.
 

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2000 Seville STS
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Discussion Starter #3
Re: 2000 Seville STS P1571, P1644, U1040

Oops, sorry! P1571: Traction Control PWM Circuit No Frequency; P1644: 1. Delivered Torque Circuit. 2. QDM/ODM "A" - Output 4; U1040 1. Loss Of Communication With Brake/Traction Control Module . 2. Lost Communication With Electronic Brake Control Module (EBCM). Prior to this, my "Service Suspension System" message came on (every day for months-- my rear shocks are kaput--compressor needs replaced, shocks are OLD and worn out, and I can't afford to replace them yet), so I don't think that's part of this new problem. Although it could be, I am NOT a fantastic mechanic. Describing me as "Shade Tree" variety is even stretching it a bit :).
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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Re: 2000 Seville STS P1571, P1644, U1040

The EBTCM is down on the body flat inside and forward of the LF fenderwell. Under the radiator "Lower hose". Has a large electrical connector that is pure murder to disconnect, clean, connect. Stuff to move out of the way. Several steel brake lines snake to/from the module block.

But that's the place to start given the codes and their definitions.

If the module itself has failed, they're astronomically expensive, so look at the website for ModuleMaster.

http://modulemaster.com/rebuilds/
 

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2000 Seville STS
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Discussion Starter #5
Re: 2000 Seville STS P1571, P1644, U1040

Thank you very much! The codes I listed in the first post were from my OBD II, these are the codes from the on-board diagnostics:

U1000 Class 2 Communication Malfunction
U1016 Loss of Communications with PCM
U1040 Loss of Class 2 Communications with ABS

P1189 Engine Oil Pressure (EOP) Switch Circuit
P1571 Traction Control Torque Request Circuit
P1644 Traction Control Delivered Torque Output Circuit

C0635 Left Front Normal Force Circuit Malfunction
C0640 Right Front Normal Force Circuit Malfunction
C0710 Steering Position Signal Malfunction

I'll check all of the grounds and connections that are easiest to reach and see if I can find a loose connection or bad ground; I've had similar issues with the CD changer, interior lights, and break/tail lights. I can't believe how dirty and corroded things are under the very nice exterior. I bought it from a ranch owner in Eastern Oregon, and I think they must have driven it down thousands of miles of dirt roads with all the windows and sunroof open. Hopefully, it will be a bad connection. I'll let you know if and when I find out for sure. Again-- is there any way that jiggling the wires around when changing the heater motor might have caused this? Is there any wires in that area that could cause this? Thanks; this is an awesome site!
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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Re: 2000 Seville STS P1571, P1644, U1040

Most likely not related to the heater/blower work.

The three C codes are (usually) each front wheel/strut/suspension control signals and the Variable Assist Steering function - a magnetic ring/sensor wrapped around the base of the steering column. All electrical connections are the first suspects, followed by harness wiring, control modules, powertrain/suspension controls.

The three U codes point to power/data loss. Has the battery died/been replaced recently ? The PCM is inside the intake airbox - the cover just under and retained by the intake resonator Torx bolt. The PCM connectors - two 80 pin connectors ! - are TIGHT and should be retained by a bolt into each one.

The P codes are oil pressure switch - on the side of the oil filter adapter. Couple of hours to remove/replace. Engine power or transmission controls. That's gonna take a diagnostic tree and maybe a GM Tech-II ($3700) to figure out.

You need a real GM/Helm service manual set - eBay or www.helminc.com OR a multi-year subscription to www.alldatadiy.com - that's the GM service manuals plus a LOT more, and it's updated while the hard copes are not.

Many more Northstar/Seville pictures/parts in my albums. Click my username, open the profile. Left column, 2 albums, 6 pages of Northstar stuff.
 

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2000 Seville STS
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Discussion Starter #7
Re: 2000 Seville STS P1571, P1644, U1040

Thanks! I hadn't really considered the battery because it starts easy. I didn't even test the voltage or look at the on-board voltage reader (I ran out of time to mess with it because I needed to get on my "Honey-DO" list), but I did clean the cables and grounds under the seat. There's evidence of a significant amount of water being back there at one time, although it doesn't appear to be recent... I noted the battery was 11 years old, though. I'll check the voltage today on the way to work. I think most of the other things that could be wrong may be way over my skill level (and pay grade!). I hope I can fix this; I absolutely love driving this car.
 

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2000 Seville STS
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Discussion Starter #8
Re: 2000 Seville STS P1571, P1644, U1040

She's running 14.9 volts according to the on-board diagnostics... it used to be steady at 14. The ABS/Brake/Trac lights are still there, of course. There are a few other anomalies I noticed on the drive to work as well: the "Service Suspension System" message displays as soon as I start her up (it used to chime and display after anywhere from a mile to 10 miles); the air compressor doesn't kick on at all; the heater only blows out of the defrost no matter where I set the climate controls, and-- here's the really strange one-- she rides like silk sliding across glass. Outside of the steering feeling a bit sluggish and the back end bouncing a tiny bit more over dips in the road, the ride is amazingly smooth, better than it was (and it was great before). And there was no slow crank, she starts right up. ???
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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Re: 2000 Seville STS P1571, P1644, U1040

The 2000 - 2004 FWD models that I have worked on all seem to start quickly, voltage ramps up to 14.6 - 15.1 for a while, then down to a steady 14.4 - 14.6.

We can't see amperage without a separate gauge and shunt, but it varies quite a bit as electrical loads change.

Water under the rear seat - either was rear sunroof drains, rear window seals, massive trunk leak - what does the bottom of the spare tire well look like ???? (Is the spare inflated to 60 psi ??)
 

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2000 Seville STS
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Discussion Starter #10
Re: 2000 Seville STS P1571, P1644, U1040

Spare was toast when I got it (looked like a black sponge, got another one from the wrecking yard), spare well was dusty with a slight rust ring above where the top of where the spare sat. Cleaned right up, just surface. I'm pretty sure someone replaced the seals around the trunk (they look newer than the seals around the doors). When changing the heater motor I pulled up the carpet and there was some surface rust residue there too, but it also looked old. I live in a place where it rains a LOT, so if it were still leaking somewhere, I'd think it would be obvious? I had some sunroof issues on a Pontiac years ago, so the first thing I did when I got it home was check the drains. Nipples on the ends were dry and free of debris, ran a hose over the top for a few minutes and they seemed to be working well. I got my STS with 168,000 miles for $1,000. Replaced the front struts ($1,500), replaced the valve cover gaskets ($108). Other than the heater noise and the compressor running a lot without seeming to change the suspension much-- and the "Service Suspension System" message coming on with a chime while driving, I haven't had a problem (it's at 181,000 miles now). If I can't figure it out and fix it I'll be sad, but at over 180k, I'm not complaining. I just really love driving this car.
 

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2000 Seville STS
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Discussion Starter #11
Re: 2000 Seville STS P1571, P1644, U1040

You weren't kidding about the EBTCM placement :) Used an electronic cleaner and a wire brush (very carefully!). Lights went out! For about 10 miles :-( Turned off the car, restarted, they were off. They were intermittent on/off. Friend told me to clean the relays, fuses, and their receptacles in the fusebox under the backseat... electronic cleaner and wire brush again. Lights didn't come back on during test drive, still didn't come on during the work commute; I can also hear the compressor in the back again (and then the "Service Suspension System" message comes on after it gets tired of trying to work right). So I'm pretty sure the grounds/connections combination was the problem(s). Also, climate control started pushing the hot air where it's supposed to again. THANKS!
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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Pull the fuse for the ELC (Level Control) compressor - If that freezes up you're in the $250 - $300 replacement business. The compressor has a solenoid control (supply/vent) head and a dessicant canister. The vent event is supposed to "blow down" the canister to remove moisture from heat of compression. Well, maybe - eventually the canister fills with snot which carries over into the compressor/head and ruins them. The dessicant canister is replaceable and should be - should be - a normal maintenance item.

Set up the system again after you find the leaks. Air lines, shock bladders.
 
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