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04 Cadillac XLR - Issues starting after HOURS of diagnostics! HELP!

Joined
Feb 24, 2018
Messages
5
Location
Utah
Good day,

Here's my XLR story, and boy do I need some help!

I sold my 2012 mustang GT and immediately wanted some power back. I came across a beautiful XLR at a local auction dealership, I decided if there were any issues I would gladly fix it. Heck - XLR Nirvana is within my grasp! Boy was I wrong!

I purchased the car and within 100 miles I started having issues. Under normal driving circumstances I started getting errors. One error would cause a chain reaction of numerous other errors on the dashboard. I will be posting a video of what it looks like below.

I've researched this car more than I have any other car and here are a few of the key notes to know:

2004 Cad XLR w/ 93,xxx miles

I purchased the car from a dealer who got it at auction. Not really sure the car history other than what carfax shows me (which isn't much)

I received the service records from the local Caddy dealership. This car has had consistent issues during the life of the car requiring lots of replacement components.



The first issues happened after hitting a rather large pothole while driving. The car immediately sensed an issue and decided to give me the "Max 80 MPH" signal. From that point on the car hasn't acted the same since.

The current issue I am extremely concerned with is the fact that it will no longer start (but has a good battery). There is a draw on the battery when I initiate the start sequence but nothing happens. There is a slight hum as I hit the button, a draw on the battery, but no firing action.

I just ordered a OBDII reader to see if any "P" codes will read (as the check engine light is illuminated while attempting to start the car) but I know the TechII scanner seems to be the device I will need. My OBD II was $20 so I want to start there before shelling over $300+ for the TechII.



I have a couple other questions regarding information on this car. It came with an aftermarket air intake system (not sure the brand off the top of my head) and it was wired for an extra set of halo lights that illuminate different colors. They used a fuse splitter setup to draw power from the O2 sensor (constant power when the car is started) could this have caused sometime of issue? I had to remove the lighting system from the electronics due to it being illegal to illuminate colored lights (It has red and blue within the illumination pattern). The fuse always stayed in but the end that would've otherwise been attached to the illuminating lights has been unplugged for a bit. Any way this caused issues?

I believe this car has some kind of aftermarket exhaust system already done as well. Could anybody please send me an underside picture of the stock exhaust system? My car has an H pipe which I don't believe comes stock thats why I ask. Also the actual mufflers themselves, not sure if they are aftermarket. This could all tie into a lean/rich fuel ratio which is causing issues with the 02 sensors (if it wasn't tuned for the work).

I want experience that XLR Nirvana! When I purchased this car I didn't know too much about the car (my mistake) but now I'm incredibly vested in learning about it. I purchased the car for the engine and the style - the other things (when working right) are nothing more than icing on the cake. I've talked with a few other car enthusiasts and ran a scenario by them that I would like to also detail in this forum.

I'm considering (if possible) doing a custom tune for the following issues / reasons, but I think the tune would have to be completed following the completion of all of the work I'm looking at doing. Here is the list:

I want to remove my catalytic converters which I know will obviously mess with the post cat 02 sensors, could a custom tune delete these 02s from the sequence of inspection?
I am looking at potentially doing an X pipe rather than an H pipe for a slightly deeper rumble along with after market exhaust (once the damn thing runs lol) Has anyone found a great sounding, low rumbling exhaust system for these cars?
I'm considering (again if possible) using the time I get the tune to actually 'shut off' the scan of numerous systems - lets be honest, I don't really need traction control with this car at stock HP. Even If i'm around 400-500HP after my other aftermarket parts, I still don't think it comes in handy. I WANT TO SLIDE CORNERS! :)!
Removing some of the annoying computer component readings I feel like will help stop this thing from firing every time a arbitrary system fails. This is of course theory and I would like feedback from experienced members/owners of these cars.

Overall I'm looking to get a good gauge on this car. I want to build this car over the years to come with big plans of this car being a sleek MONSTER, but at this point I'm ready to just drive it (or pushing it) off a cliff and collect the insurance on it lol! Please help!
 

pure zen

Seasoned Member
Joined
Mar 12, 2014
Messages
787
Location
AZ
My XLR/V(s)
2005 Crimson Pearl XLR
Pot hole kick-off,,,,

quote: ",,,,at this point I'm ready to just drive it (or pushing it) off a cliff and collect the insurance on it lol!"

:laugh: Probably not a bad idea :reddevil

93,ooo mile auction car......one I would have strayed away from, Sounds like you have some big issues with this first production year car, and a $20 OBD II reader probably isn't going to help you much. Should have kept the Mustang GT, and made it a 'monster' > JMO

Good luck,,,I'm no help on this one..

p z
 

BeardBros

Seasoned Member
Joined
May 8, 2017
Messages
147
Location
Central Illinois
Project cars - gotta love em. I like the challenge of bringing something back to life that has been written off by others. Here are my thoughts on your project.


  • You have to look at your investment first, tally up everything you want to do to this car including the repairs and is it less than buying something that is already done, save lots of an hours
  • As for the issues your car has, anything can be fixed. You need to read the codes and repair the items they point to.
  • The "Max 80 MPH" signal points to something in the suspension/ride control system
  • Starting problem - if the engine does not even rotate then loose battery/ground connections, low battery, starter
  • Put the O2 sensor wiring back to stock, these cars are very sensitive electronically
  • There have been performance mods done on these cars. If you do a search in the forums you will find alot of info on the things you are talking about and there is a member on here, gizmoQ, who has done some. here is his page. ELWOOD :: 2006 Cadillac XLR-V
  • here is a picture of a stock exhaust system on a 2004 XLR, you can see the H pipe crossover.
  • IMG_4820.jpg
 
Last edited:
Joined
Feb 24, 2018
Messages
5
Location
Utah
Thanks for the information!

I have since put the 02 wiring back as is.

The battery is about 4 months old, was fully charged when it was installed, and still maintains a good electrical output.


UPDATE:

I removed both battery connectors in hopes of letting the reset. After reconnecting the battery I tried to start the car again. The first 2-3 clicks of the start button and it didn't start. Then randomly.... FIRED UP! I let the car run for a bit, all the codes came back on (I have a video but am unable to post it in this thread for some reason). Its like a christmas tree though. Service ABS, Service Stabilitrak, Service Radar Cruise, Service vehicle soon. I turned off the car after idling for 5+ minutes, tried to start it back up and the same issue occurred - no signal from the starter :(


I started thinking about this further and I'm trying to consider all things possible. Because of the aftermarket air intake system could there be some type of system failure when the car is reading something? Maybe a handheld tuner was used and its causing the system to go hay-wire?

Any other ideas are appreciated!
 

xlrlist01

Seasoned Member
Joined
Oct 31, 2013
Messages
252
Location
HSV
Thanks for the information!

I have since put the 02 wiring back as is.

The battery is about 4 months old, was fully charged when it was installed, and still maintains a good electrical output.


UPDATE:

I removed both battery connectors in hopes of letting the reset. After reconnecting the battery I tried to start the car again. The first 2-3 clicks of the start button and it didn't start. Then randomly.... FIRED UP! I let the car run for a bit, all the codes came back on (I have a video but am unable to post it in this thread for some reason). Its like a christmas tree though. Service ABS, Service Stabilitrak, Service Radar Cruise, Service vehicle soon. I turned off the car after idling for 5+ minutes, tried to start it back up and the same issue occurred - no signal from the starter :(




I started thinking about this further and I'm trying to consider all things possible. Because of the aftermarket air intake system could there be some type of system failure when the car is reading something? Maybe a handheld tuner was used and its causing the system to go hay-wire?

Any other ideas are appreciated!

If you are getting all sorts of weird codes, first stop is replace the battery. Even if it is enough to crank, still replace it. XLRs are amazingly sensitive to battery problems.
 

BeardBros

Seasoned Member
Joined
May 8, 2017
Messages
147
Location
Central Illinois
I agree, put a new battery in it. Also, are you sure the alternator is charging the battery while it is running? You need to put a meter on the battery when the engine is running, it should be above 14 volts. Also you need to get a scanner and read the codes instead of guessing what is wrong, you will keep chasing your tail trying to figure out what is wrong.
 
Joined
Feb 24, 2018
Messages
5
Location
Utah
So I made a little headway in finding what the issue was.

Battery is fine (new battery, fully charged)
I have an external battery reader that displays the battery power output while running and it is indeed above 14 volts. Good on that front.

I hooked up a portable OBDII Reader that I purchased for $20 on amazon, prior to starting the system read the following failure codes:


U0100 - Lost communication with ECM/PCM "A" (I assume they have two different ECMS as this one is labeled A?)

P0700 - Transmission Control System (MIL Request) (not a clue where this is coming from but assume is has to do with the lost connection to the ECM)

U0001 - High Speed CAN Communication Bus

I did also note that both ECU 1 & 2 gave me a green light so no issues there.



The car after 100 failed attempts sat with the battery 100% disconnected for 2 days, when I put the cabled back on I haven't had an issue since.

Random and frustrating, but for now I'm back in XLR Bliss - I would like to permanently fix these issues however!
 

BeardBros

Seasoned Member
Joined
May 8, 2017
Messages
147
Location
Central Illinois
here is something I found online that may help you, had the same issues you were describing -

[h=2]Re: code 0700 & u0100 cadillac[/h]
Update: I took it back to the person that replaced the EMC late last spring to see if he could find/fix it. It seems that the computer went into a sleep mode but didn't wake up when the key turned on. The emc was fried again he couldn't find the short. He has a friend that works at the cadi dealer and had him look at it. He removed the fuse box out of the engine compartment and found a wire harness that connects to the bottom side of the box that had a bad/burnt wire in it. He repaired it, cleaned all grounds on the car and replaced the EMC. They ran it on and off for a couple hours of days then let it set for 3-4 days and it seems like it may be fixed. Don't know what the wire was to or for. FYI the cadi guy saw my jumper wirer (purple wire to + battery) and said that a big no,no and a good way to tear up the tranny.
 
Joined
Feb 24, 2018
Messages
5
Location
Utah
That's an awesome find! I keep thinking it has to do with the fuse box!

I will try taking it out and ensuring none of the wires are shorting very soon. I will keep you all posted :)!
 

lextoy

Seasoned Member
Joined
Mar 29, 2014
Messages
353
Location
philadelphia
My XLR/V(s)
2007 Liquid Amethyst
multiple people have confirmed that when disconnecting the battery the car will not recognize the remote key for 10-20 minutes. heres what i did when i had to change my battery...
when i replaced my dead battery it took me 1/2 hour to get the car to recognize any key fob again.
so dont panic.
after multiple door opens and closes, pressing the brake pedal, locking and unlocking with the fob,
putting the fob into the glove box slot, about a dozen attempts in various order...
eventually it recognized and restarted. after that havent had a fob problem since.

if you disconnect the battery, likely you are encountering this issue when trying to restart.
once you get it restarted, then your other codes etc kick in and disable the car, forcing you to disocnnect battery
and start whole process over.

it is possible that your RCDLR module, the one that controls the starting, key fob recognition etc, is teh culprit of your starting issues
but i am no expert.

i did experience the failure to start when i replaced my battery. but havent had an issue since (4 yrs)
 
Last edited:

David_B

Seasoned Member
Joined
Aug 31, 2014
Messages
446
Location
SE Michigan
My XLR/V(s)
N/Z
Sounds like a serious grounding problem to me.

I would start at the battery, follow the ground cable back and clean every major connection in the ground tree.

I don't know where it is, but there's a thread on a ground near one of the rear wheels that has caused people grief too.

I had a car repaired after a crash once, it was doing similar things, ended up being the repair shop had completely forgotten to install a major body grounding strap.
 
Joined
Feb 24, 2018
Messages
5
Location
Utah
I'll give this a go and let you know. As of the last 2 weeks I have had zero issues with the cars electronics and no failed starts. I haven't been using any of the extra electronic functions within the car thinking that might help me from having issues. No cruise control, no manual shifting, and the radars aren't utilized without the cruise control initiated.

I will do an entire engine inspection once it gets a bit warmer here!



Sounds like a serious grounding problem to me.

I would start at the battery, follow the ground cable back and clean every major connection in the ground tree.

I don't know where it is, but there's a thread on a ground near one of the rear wheels that has caused people grief too.

I had a car repaired after a crash once, it was doing similar things, ended up being the repair shop had completely forgotten to install a major body grounding strap.
 

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