Bad Throttle Linkage??

MrO · Jul 13, 2011

Hi All,

New member... Family member has a 2004 XLR. Had the usual dead battery issues but it always ran good... Now this problem has popped up:

() Rain water in trunk pocket where wiring harness connectors are. Connectors were completely submerged for a few weeks due to a kink in the pocket's drain hose. Convertible top stopped functioning.

() Drove car to dealer to diagnose. They just wanted to start replacing things until it started to work. Decided not to have them do the repair. When the car was picked up it had a serious lack of acceleration (that the dealer said they had nothing to do with) :pat:

Now the car starts and idles rough, and pressing the gas pedal has no effect on idle speed.(stays at about 1000rpm) It's like the pedal isn't connected to the throttle linkage.

This all started with the soaked trunk connector... Any suggestions on where to start looking? I'm going to do a serious cleaning of the connectors this weekend. I just need some "food for thought" before I start to troubleshoot. Hoping a module isn't shorted out. Ordinarily I would just take it into the dealer and have them run a diagnostic with the Tech 2 unit, but... it's undriveable now due to the throttle issue, and I really don't want to pay to have it towed to and from the shop... The suspension service warning message is also appearing on the dash display.

Thanx in advance,

Mark (SF Bay Area)

Cadillac Tech · Jul 13, 2011

MrO said:
Hi All,

New member... Family member has a 2004 XLR. Had the usual dead battery issues but it always ran good... Now this problem has popped up:

() Rain water in trunk pocket where wiring harness connectors are. Connectors were completely submerged for a few weeks due to a kink in the pocket's drain hose. Convertible top stopped functioning.

() Drove car to dealer to diagnose. They just wanted to start replacing things until it started to work. Decided not to have them do the repair. When the car was picked up it had a serious lack of acceleration (that the dealer said they had nothing to do with) Now the car starts and idles rough, and pressing the gas pedal has no effect on idle speed.(stays at about 1000rpm) It's like the pedal isn't connected to the throttle linkage.

This all started with the soaked trunk connector... Any suggestions on where to start looking? I'm going to do a serious cleaning of the connectors this weekend. I just need some "food for thought" before I start to troubleshoot. Hoping a module isn't shorted out. Ordinarily I would just take it into the dealer and have them run a diagnostic with the Tech 2 unit, but... it's undriveable now due to the throttle issue, and I really don't want to pay to have it towed to and from the shop... The suspension service warning message is also appearing on the dash display.

Thanx in advance,

Mark (SF Bay Area)

The XLR is a drive by-wire, no throttle cable. I would try disconnecting your neg. battery cable and wait 30 seconds or more before re-attaching the cable. See if that helps.

ChicagoDave · Jul 13, 2011

MrO said:
Now the car starts and idles rough, and pressing the gas pedal has no effect on idle speed.(stays at about 1000rpm) It's like the pedal isn't connected to the throttle linkage.

... The suspension service warning message is also appearing on the dash display.

Thanx in advance,

Mark (SF Bay Area)

Mark - I have experienced something very similar - its only showed up a couple of times - and it went away rather quickly (I think I just put the car in Park, then back to Drive and all was OK). I'm thinking the system just needs to be reboot, as Bruce suggests. Hope it fixes your problem. :dunno:

MrO · Jul 15, 2011

Woo-Hoo!!

Hi Bruce and Dave,

Thx for the advice. It's purring like a kitten now with normal throttle response at idle... :rocker:

Get comfortable, this is a long one... Here's what I did:

() Started the car to wake up the evil spirits. Yup, died the first two tries, and then I was able to tap the accelerator pedal on the third try to keep it idling. Once idling it ran like crap and still had no throttle response. When I pushed the accelerator pedal it hesitated a bit but maintained it's 1000 rpm idle. Turned it off... :willy_nilly:

() I took Bruces advice and popped the hood, disconnected the battery, waited a few minutes, and to be sure of a total circuit reset I held the loose + and - battery cables together for 15 seconds or so... I then reattached the battery cables to the battery, and tried to start the car.

Same symptoms... Rough 1000 rpm idle and no throttle response. :pat:

() Keeping the engine running, I then tried Dave's suggestion and cycled the shift from Park to Drive a few times. The idle was really rough now, pulsing a few hundred rpm and rocking the car, but it seemed to level out when I had the car (with the brake on) in Reverse or Drive. More cycling then it was rough no matter what position the shift was in. :dunno:

So... I put it back in park and noticed some response on the throttle. I could bring it from 1000 to 2000rpm in park. Not much control in between, pretty jumpy. More shifting and throttle pumping and the evil spirits slowly went away... Then... Purred like a kitten at about 700rpm.. And smooth throttle response thru the rpm range

Now the car was warmed up to operating temperature, idling SMOOTH and I was feeling pretty good about myself... I shut the car off. Restarted it and it died. Started it again and kept it running with light gas pedal action. Returned to a smooth idle..

We'll see how it does tomorrow when it's a cold start. Next step: A few test drives around the 'hood, and then locate and drive it to the shop and have a certified technician (I'll definitely ask) get and error codes on the Tech 2 unit as the check engine light remains on. Should get some interesting codes from that.

Anyway thanx SO much guys :worship:

I'll keep y'all posted on the diagnostic results... After I'm sure it's running right again, I'll tackle the issue of the retractable top plugs in the trunk.

Cheers,

Mark (The chilly SF Bay Area)

MrO · Jul 30, 2011

Mission Semi-accomplished...

Well, the saga continues. (Grab two beers and get comfortable, this has turned into a blog)

After many many hours cleaning the corrosion off the wiring harness connectors in the trunk pocket, and replacing the control modules that they were attached to, the trunk opens and closes fine now, and the “Service ride control” message is gone on the instrument panel display, but the convertible top in still inoperative. The idle is slowly getting better as I drive it around a bit with the new fuel and fuel system cleaner added to the gas. Here’s what I did:

Disconnected the battery… Started with pulling the ride control and retractable top modules out of the trunk pocket for inspection. They were a crusty MESS. (mind you, these sat under water for a few weeks) Opened them up to inspect the circuit board. They were a equally crusty mess. Cleaned the crusty residue off both boards with my water/citric acid solution. Worked GREAT as usual, the boards came out looking like new. I was able to inspect the circuitry now.. Ughh… Burned out traces, fried components, bad via’s… If I had a circuit schematic I MAYBE could have repaired them, but it would have taken HOURS with no guarantees. Nope these circuit boards were toast… I’m generally angry that the boards were not fuse protected. There appeared to be fusable links on both boards, one of which on one board burned open, but not in time to save the board… Curses on that board designer for not adding a few cents worth of circuit protection in-line with the power connection. :rocket:

Ordered new modules from www.gm-partscenter.com which were shipped from a distributor called Randy Curnow in Kansas. 25840734 Retractable top Module ($306) and 10348979 Suspension Module ($415) with free shipping… Took about a week to get ‘em. While I was waiting for the modules I ultrasonically cleaned the crusty harness connectors. (Thank you GM for making the dozen or so connectors unique so reconnecting them was a breeze. :patriot:

Almost makes up for your crappy circuit board protection) 8 minutes per connector in the water/citric acid solution cleaned ‘em right up. Blew ‘em out with compressed air
Then I tackled the crusty motor assembly in the trunk pocket. The hydraulic casing seemed to be sealed pretty well, so I just cleaned the outside of the assembly. The motor needed attention though so that the only thing that I had to remove. After removing the black plastic cover to inspect the motor my heart sank… This motor had the same crustacean residue as the PCB modules. :pat:

No way this thing was going to work in it’s present condition. I didn’t want to drop another $1000 on a new hydraulic/motor assembly, so I decided to try to clean it up. Into the ultrasonic bath it went with the water/citric acid solution. 8 minutes later it looks like new. I blew it out and fired it up the next day with a DC power supply at work. It started right up and ran fine. WHEW!! So I reinstalled it onto the pump assembly. I noticed some of the hydraulic fluid leaked out of the pump block. Cleaned that up walked away from the job until the modules arrived…

Ok home stretch… Got the modules… Installed them into their positions. Reconnected the wiring harness connectors. Then noticed that the pump reservoir fluid level was low. CRAP!! Another delay.. Found it online from GM for about $75 for 500ml… What the ???? $75????? NO WAY!!!! Googled the part# for an alternative and found that the SAME fluid is used in SAAB’s under a different part #: 93165227. Only it’s $43 there. I still choked on that a bit but at least I saved some $$.. Went to the SAAB dealer to pick it up. Got it and saw it was labeled in German but had the GM insignia on it… hmmm…

So.. refilled the reservoir to the proper level. Prettied up the trunk compartment a bit. Then
() reconnected the battery
() Got in the car and held the two electric window switches up for 10 seconds to reset the position sensor on the computer module. (the retractable top needs this step to operate properly after battery disconnect?)
Pushed the trunk button on the dash and the trunk motor whirred to life and opened the trunk. (SWEET!!) Got out of the car and pushed the close button and it closed :rocker:

Got back in the car and tried to lower top… Nothing… :willy_nilly:

Checked the fuse box and circuit breaker and everything looks up to snuff… Hmmm…

Well time to end this saga...
Mission semi-accomplished… The water damage has been repaired to the best of my ability. 2 of the 3 electrical issues are resolved ( Suspension error message and Trunk lid operation). The car is running MUCH better.. Just the top issue and Engine Check Light issue now… I think it’s time to take it to the pro’s at the dealership for a diagnostic… Depending on that outcome I may get a service manual and dive into this again <OR<or>> we may just sell the car as-is for a few thousand $$$ discount… We’ll See… I’ll let y’all know what happens at the dealer next week…
Cheers,
Mark (SF Bay Area)</or>

MrO · Jul 30, 2011

Retractable Top Programming?

Hey Guys,

Do I read right that after replacing the retractable top module in the trunk well, it has to be re-calibrated with a a Tech 2 by the dealer???

Thx!!

Mark

onalaska · Jul 30, 2011

That is correct. You need a Tech2 so the module can "learn" the top position sensor values. It's a simple process that your dealer can preform for you.

MrO · Jul 30, 2011

Thx!!

Hi "OnAlaska",

Thx for the quick reply. I've been holding my breath on this one. This is the answer that I wanted to hear... Hopefully the Caddy dealer a few blocks from my house has a Certified XLR Tech on staff... Speaking of which, you guys may enjoy this post from another forum about certified techs:

"Speaking of Certified XLR techs, I've had a nagging minor issue that I have been putting off taking the car into a dealership until something bigger came along. Something did. My car started filling the garage with overpowering gas fumes this past week. That qualifies as BIG in my world, since my wife insisted I park it outside where it would asphixiate her in her sleep or blow our house up. (This logic was tough to argue with.)

Being relatively new to Sacramento, I called the nearest Cadillac dealership with a conversation that went something like this:

"This is Service."
"Hi, I need to find out if you have a Certified XLR technician."
"All of our technicians are certified."
"Yeah, I would hope so, but do you have an XLR-certified tech?"
"All of our technicians are certified."
". . . How many techs do you have?"
"About a dozen. We work on lots of XLRSs here"
"Of that I have no doubt. And all of them are certified to work on the XLR?"
"No."
"How many of them are certified?"
"I don't know."
"So you don't really know if you have a certified tech or not?"
"That's correct."
(Short pause. . . ) "Can I speak to the Service Manager please?

The Service Manager was much more helpful and assured me they had a certified tech. After that, I drove down, met all the folks I need to know, and left them with my car. So even though it's a little more work, it's worth it to find the right dealer. Your wallet will thank you."

(turns out this was a known fuel tank hose problem covered by a service bulletin)

CC

XLRATING · Jul 30, 2011

After reading various disasters on here related to that drain hole, I checked mine. All was well except it was just that - a hole, no tube. Does anybody know if an '06 is supposed to have a tube? :willy_nilly:

Maybe it's a good thing because I have nothing to kink ...

GizmoQ · Jul 30, 2011

XLRATING said:
After reading various disasters on here related to that drain hole, I checked mine. All was well except it was just that - a hole, no tube. Does anybody know if an '06 is supposed to have a tube?

Maybe it's a good thing because I have nothing to kink ...

My 06 V has just a hole, also.

MrO · Jul 31, 2011

XLR Trunk Compartment Drain

AMENon the absent drain hose.. It's fool-proof now on draining that inevitable flood... I just snipped the flap off the bottom of my '04's drain hose. Now you can see the ground looking from the compartment side... IMHO there was never a need for a hose anyway... (makes me want to just remove the cursed thing completely... I'll ask the dealer about the hose or lack there of on later models... I'll do my final summary post next weekend...

Cheers,

Mark

MrO · Aug 4, 2011

Woe is Me

OK... So... Just got the XLR back from the dealer to check out 3 issues:

1) Top does not retract after the trunk module replacement, but trunk lid opens fine.. I assumed that the module just needed to be reprogrammed..
((estimate for repair: $240 ))

2) Diagnose check engine light on instrument panel.
((estimate: $150 ))

3) Getting into the car the morning of the drop off to the dealer the instrument panel display reads: "Flat rear tire. Do not drive over 50mph"... Grrrreat...

Checked the tire pressures: all ~32psi...

I added that to the check list..
((estimate: $75 ))

They couldn't fix any of the problems, so I retrieved the car. Here's the scoop:

I really liked all the guys I talked to at the dealership... Good people... The car attracted a lot of attention as usual.. I called 'em EOB the next day after the drop-off to get a status. The Serv. Mgr says the XLR certified guy is struggling with the top and engine light issue... The top module programmed fine, but the top still wouldn't work.. Told him to continue fighting the good fight and keep me posted.

Get a call mid-day on day two in the shop from the service guy saying:

<> They were able to reprogram the top module, but the top still did not operate. They would need more $$ to further diagnose and repair the top. I declined

<> They checked the PCM DCT's with the Tech 2 and it puked out these codes: P0068_P0300_P0102_P2108_P0101_P1101_P0106_P0013_P0010_P0102_P2108 and U0101... Crap!! are there any codes it missed??!!

Fuel pressure was OK at 60psi and there were no obvious vacuum leaks, and the engine idles smooth at 800rpm(ish), and drives fine. They programmed the PCM with the latest calibration, but the symptom still present. They recommend a new Mass Air Flow Sensor and new MAFS harness connector, and then recheck for error codes... Oh yeah, they need more $$ to do this... I declined

<> They verified the rear flat tire message and tried to reprogram the the system, but sensors failed and were not communicating... Will need two new sensors... More $$ needed.. I declined

<> During 20 point inspection they found the front brake pads worn out. I told 'em I would fix that myself..<> They also noted that the water pump had some old water leak traces..Nuts to that repair right now too...

Sooo... Two days in the shop and over $400 in "repair costs" I have a car with the exact same problems that I dropped it off with.

I can't help but be unimpressed... I'm half tempted to get the manual and try my luck with it... It sure sounds like an electrical issue (harness connectors or sensors) to me. The sudden "rear flat tire" sensor issue sends up some red flags in my electrical evil spirit manual... :dunno:

So... Need some advice guys...Any suggestions?? (FYI... IMHO I'm pretty good with car repairs, and am a EE by profession... I've been a shade tree mechanic for many moons... I just don't enjoy doing it that much any more... But if it will save me a few thousand more $$$...hmmmm..)

Cheers

Mark (Sunny, Cool SF Bay Area)

onalaska · Aug 4, 2011

Wow! sorry to hear the bad news. I guess I am lucky to have a dealer that sees enough XLRs to be able fix things. Fortunately all of my problems have been covered by warranty, but that will end soon. The first thing I did when I bought the XLR was order a factory service manual from Helm, Inc. I am still powerless to do most things without a Tech 2 and that may be in my future. I can use it on our other vehicles also. Without one you are flying blind. Bruce should be able to help you with the trouble codes, sometime more than one are related to a common problem. More than one of your problems may be related to the water issue and a bad ground somewhere. Good luck!

ccclarke · Aug 4, 2011

Mark,

Even with a shop manual, troubleshooting an XLR (especially with lots of powertrain DTCs) takes a Tech 2 for all but the most trivial repairs. Once you start leafing through the shop manual, you'll see what I mean.

You may have bad roof sensor(s). These are pots that are squirrley at best, unreliable at most. Too bad GM didn't use real encoders instead of using "counts" (proportional voltage.) The must be bonded to ensure they don't work loose and give faulty readings. (Poor design --secured by one fastener.)

The RCDLR receives the signals from the TPMS sensors. It's worth a look. The sensors are fairly reliable. Two bad at once is suspect to something common between them (the RCDLR.)

Inspect/clean the MAF sensor as necessary. It might be a cheap fix.

CC :wave:

MrO · Aug 4, 2011

Down But Not Out

OK... So I see this 2 year old posting on the forum:

"A new issue was discovered that is appearing in older XLR and some STS models with the Northstar V8. My layman's explanation, based on a much longer discussion with the Tech is that, over time, the heating and cooling of this particular engine model results in the air intake manifold bolts loosening and backing out, as the seals leak a vacuum occurs allowing unmetered air into the system. The computer tries to adjust but eventually exceeds limits and throws all the codes typical of the other problems. Solution was to install new seals and make sure the bolts are properly torqued. Those with XLRs and unexplained lights may want to have this item checked, the tech said it was pretty obvious the bolts were loose upon inspection"<!--[if gte mso 9]><xml> <w:WordDocument> <w:View>Normal</w:View> <w:Zoom>0</w:Zoom> <w:TrackMoves/> <w:TrackFormatting/> <w

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I might be grasping at straws here, but this makes sense to me... I'm going to check that intake seal for leaks.. Back in the day I used propane to check for vacuum leaks (engine running, when the gas hit a vacuum leak, the idle jumped up). Does this trick still apply to these high tech engines?

Also, CCClarke, thanx for the tip on the top sensors and MAF sensor. I have no clue where to look for these buggers though, so I may have to get the manual to locate 'em... I know what the MAF looks like (thx google). I just don't know where it attaches to the engine. And I know there are 3 sensors (switches) for the convertible top but don't know where they are either...

Cheers,

Mark

MrO · Aug 5, 2011

Check Engine Light Reset

A thought just occurred to me... If by some stroke of luck I stumble across and repair the issue(s) tripping the check engine light, will the warning light circuit automatically reset and turn itself off? <or> does that annoying Tech 2 unit have to reset it?

Thx!!!

MrO · Aug 6, 2011

New Post Thread

Hey All,

This post was getting too long and was straying away from the original thread title so I started a new more relevant thread called: " Engine Sensors_Top Switches and Check Engine Light " I'll be posting questions and updates there now... Thx again for all the excellent input up to this point.

Cheers,

Mark