: Just got exhaust work done and now I'm getting some codes... Advice? 2002 DTS

07-02-11, 03:32 AM
Hello all... I have a 2002 Cadillac DTS with 96,000 miles... The car runs great, idles good, and hasnt given me any problems yet. I changed the oil last week and this week decided to put a custom exhaust on... I still have the catalytic converter, but I deleted the resonator and ran 3 inch pipe from the cat to a 2 1/2 inch Y-Pipe with Summit Race Mufflers... The car sounds great now. The shop who I deal with has done exhaust work on my 2009 Nissan and 1987 Caprice with no issues. When I got home, I noticed the "Service Engine Soon" light was on... I read the sticky on here and read the codes for the computer and this is what I came up with... So far, the car starts good, idles good, and drives good... These are the codes I have...
U1713- Loss of Front door module to window motor high speed comm.
U1301- Short to battery
U1000 IPC- Current
U1016 IRC- Loss of Class 2 Communication with VCM... Can also mean loss of communication with PCM
Do any of these codes have anything to do with the exhaust work I had done, or just coiencedence? Are any of these codes serious? What are some things I can try to see if they will go away? Thanks for any assistance guys.

07-02-11, 11:07 AM
None of those are (directly ??) related to the exhaust work.

There WAS a recall in the 2001 -2002 Northstar series for a U code - "Loss of ignition signal to PCM". Your local Cadillac dealer may still be able to get to your car's GM database to find out if the recall was done.

U1000 is a "Class2 communications malfunction code" - maybe, just maybe, the cutting and welding caused a short ????? just a guess........

Go back through the code pull sequence and at the end answer "YES" to the question "Clear all codes". Drive for a few days and see what pops up again.

07-03-11, 03:07 AM
I cleared the codes last night and drove the car to work at 4pm and got no codes... On the way home though, the SES light came back on and this is what I got for codes...
PCM P1860- Current- TCC PWM Solenoid Circut Electrical
AMP U1064- History- Loss of Communication DIM
IPC U1000- Current- Class 2 Communication Malfunction
Are any of these codes serious? What can I do to correct them? Are they related to the exhaust work? I was thinking about disconnecting the battery for 30 seconds and clear the codes and see what happens... The TCC I'm assuming is the Torque Converter Lockup... Any help would be appreciated. Thanks!

07-03-11, 08:06 AM
Maybe they messed with a ground wire?
Were they mig welding on the vehicle?
I have never had it happen but have heard tales of problems after welding on a car.

johnny kannapo
07-03-11, 01:08 PM
They may have broken the o2x sensor internally. They are made form porcelin and would not tolorate a drop or other shock.
If you remove it & shake it you may hear the broken porcelin rattling inside. They are some what fragile that way.

07-03-11, 02:38 PM
Thanks for the tips... How many O2 sensors are there on the DTS? I'm guessing between 2-4... Is the TCC code due to a short from welding or can it be faulty? Is there anything I can disconnect to check the TCC solenoid or any grounds I can check? Is it possible that the welding caused damage to the ECM or its components? Hopefully these codes are repairable and not too expensive.

07-03-11, 03:14 PM
Not sure what to say:(
I did look for you though.

10-15-2006, 05:47 PM
WeldingWeb Tradesman Join Date: Oct 2006
Posts: 226

Re: vehicle welding precautions


Good advice from all!!
Summing it up, Disconnect battery, keep ground connection as close to the work as possible. Do not connect ground clamp on or near anything mechanical or electronic; solid frame or chassis connections only. And finally, check BOTH sides of your work for problem areas before you begin welding.
It would be a very good idea to keep a garden hose pressurized and at the ready, and a bucket of water with several soaked rags in it. Make sure you are wearing a welding mask and gloves. Stop and check periodically while you are progressing with your work. Undecoating will smolder and burn, as will the factory-applied seam caulking.
And finally, protect your glass from the possibility of spatter. I understand you are working on floorboards with a mig welder, so this is a remote possibility, but it merits mentioning. Any contact with hot spatter will immediately cause pocking of the affected glass. Using a grinder near the glass will do the same thing. (Somewhat) bitter experience talking here.
Good luck with your project!!


---- Did they disconnect the battery?
--- Did they weld any mounts/hangers under the vehicle?
--- Did they Mig - Tig or braze weld.

This site says there is a vehicle ground device available.


Most manufacturers mention this in the workshop manual. Generally disconnect the battery, alternator and electronic devices (ECU, radios &c)

Do refer to the manual though, some cars are so sophisticated these days that disconnecting things can upset them and you have to perform certain rituals once everyting is re-connectord.

Keep the earth clamp as close to the weld as possible to avoid stray currents.

07-03-11, 03:49 PM
Thanks for the tips... How many O2 sensors are there on the DTS? I'm guessing between 2-4... Is the TCC code due to a short from welding or can it be faulty? Is there anything I can disconnect to check the TCC solenoid or any grounds I can check? Is it possible that the welding caused damage to the ECM or its components? Hopefully these codes are repairable and not too expensive.

3 O2 sensors: B2S1 is in the left exhaust manifold collector, driver's end. B1S1 is in the top center of the right exhaust manifold. B1S2 is the after-cat sensor (and probably the most susceptible to exhaust work damage).

TCC solenoid is controlled by the PCM through a multi-pin connector at the front side of the transmission, down low. You'll need a GM wiring diagram for this pinout. TCC faults - either the solenoid itself freezes or the circuit develops a short - are not normal, but not uncommon, either - it's doubtful that welding would fry the solenoid itself.

Welding can possibly damage the PCM (all in one: Powertrain Control Module....$$$$ you don't want to know).

johnny kannapo
07-03-11, 07:10 PM
+ 1 on the possibility of welding damage.

07-04-11, 04:45 AM
Thanks for the replies guys... I will check the after-cat O2 sensor for damage... If that is not damaged as stated, what other options do I have? If the sensor checks out ok, I was thinking about taking it to a dealer to have it looked over... Would there be any other things I can check to see if the PCM is fried? How much would I be looking at if I needed to replace the PCM? I heard the TCC repalcement is a $1000 job... I was going to check the connection on that as well and make sure its secure. I just hope I didnt damage anything... They MIG welded the exhaust... I dont think they added any additonal hangars, but I will take a look. Overall, what could be the worst case scenario? PCM and/or TCC replacement? I was going to check the grounds as well... just for reference, where are the grounds on the Northstar? Thanks guys!

07-04-11, 10:07 AM
If the PCM was "fried" the car plain, flat would not run. LOTS of stuff would not work - discount the PCM "fried" idea.

TCC solenoid replacement, by a dealer, is more on the order of $1500 or more. Book rate is right at 11 hours labor. Someone in here did the job like open heart surgery (transmission in the car) - look down in Cadillac Tech Tips.

Grounds - you'll NEED either a real GM Service Manual or subscribe the car to www.alldatadiy.com (http://www.alldatadiy.com)

07-05-11, 02:42 AM
Thanks for the help guys... I will be adding my Cold Air Intake on Thursday, so I will be checking out the tranny pigtail and rear O2 sensor to see if they are damaged... If I come up with nothing, I am going to take it back to the shop I got the exhaust done at and see if I cant get something done to help take care of the issue... Where are safe jack/ jackstand points on a 2002 Caddy DTS? Thanks! I will post back with any results I may get.

07-05-11, 07:48 AM
FWIW, Your car already has a perfectly functional CAI straight from the factory - it flows more air than the engine can handle at WOT redline. Most aftermarket "CAI" installs are actually bling HAI rigs which give the impression of more "power" through intake noise increase. Change to a (larger media area) WIX panel filter and you have just accomplished what that silly cone filter does for $7.95. Trace out your intake - and remember - that OEM intake also flows cool air over the PCM - don't screw that up.

I use a ScanGauge in my STS (mostly stock intake ducting), and one of the 12 gauges I monitor constantly is intake air temps. On the highway the temp runs anywhere from 4 to 9 degrees over ambient. Near suburban, about 8 - 15 over ambient, and stuck in city traffic it can go up to 150 degrees because there's very little airflow through the intake at low speed/idle. ANY intake will heat up under stop & go conditions. Get out of the city and airflow into the engine increases, intake temp drops back to the first set of temps.

Remember also that these engines have heated throttlebodies - the TB is mounted to the water crossover casting, so the bore runs very close to coolant temperature - 200 degrees at normal cruise...............

Jack/stand points............careful............check a GM service manual. There are 4 hard pads at the body - behind the front wheels and in front of the rear wheels, as well as a couple of places on the engine cradle and suspension attachment points. You really need the jacking diagram for this..........too many stories of squashed rocker panels and bent door edges.

07-06-11, 05:53 AM
Thanks submariner... I will see if I can locate a GM manual for safe lift points on the Caddy... I will post back on Thursday or Friday with more information.

07-10-11, 04:27 AM
I got a chance to check things out on my 2 days off... I checked the rear O2 sensor, that was good. I also checked the 20 pin connector to the transmission... thats good and I disconnected the battery and the SES light was still on... I took it to a shop that didnt charge to put the car on the scanner and it still came back with the 1860... Im going to do alot of asking around and see what the best quote I can get is... Im also considering doing it myself, but I am really not into FWDs...

07-13-11, 04:37 PM
Hello Everyone, I do not know the answer to your electrical problems, however for certain I can tell you to never,never weld to anything with a battery! I don't care what uncle knows everything say's, chances are somethings going to get jacked up.I've been welding since I was 10 years old, have had a couple of 40 hour week jobs,now I own my own shop for the last 20years,mig-tig- heli-arc- stick-plasma cut,current is current, the more toys on the item increases the chance of disaster...lawn mowers, boats,trailers, motorcycles-campers, generators....Chances are the ground was grounded to the frame and not the exhaust, even with the battery totally disconnected the only route the current had was through the cars componets....sometimes you get lucky...sometimes you dont..sometimes you blowup other times you walk away...use a pair of jumper cables from the frame to the engine block for an additional safeguard if in doubt....a one inch weld with any thing but a tig or heli-arc has close to 1000 sparks...a ten minute weld job should be preceeded buy at least an equal amount of time for the protection of the surrounding area..brake lines-, shocks-radiators,hoses,and all windows closed ..a hot spark can shoot out ten foot and bounce back twelve still hot...Everybody knows somebody thats a welder,there are alot of great ones that do it in their garage,thats great! YOU have to be the one thats makes sure your stuff is safe guarded..even in pro shops.fyi ,I do stainless -all castings alum,iron ,steel, I just repaired a bronze statue of Zuess. I have learned a lot and like to pass on any information that may help someone. If it's allowed I can put my shops web site address down next time. Have a great week.....Ed

johnny kannapo
07-15-11, 11:32 PM
use spike protection, I never had a system failure.