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Discussion Starter #1
Hi all,
I've got a first gen with 20k miles on it. It's been absolutely babied since new. A couple of years ago it has developed a stall when cranking the wheel to the left (at fast or slow speeds) and recently it has developed a "jerk"/stall driving at cruising speeds every once and a while once the car has been driven for a bit. It does this on a full or close to empty tank of fuel. There aren't any codes with my OBD2 scanner, but that's not to say that the dealership won't find any codes specific to the car. I'm taking a SWAG at it being either the cam or crank position sensors and want to get an idea of what the work is that involved with changing them out. I don't see anything in the DIY thread about it. Does anyone know of a write-up on what I need to do in order to change either of them out?
 

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In the absence of codes, I would first freshen the engine grounds on the back of the cylinder heads as well as the ground at the base of the hood strut. These grounds are critical to the power train management system. These grounds oxidize (with time/regardless of mileage) and interfere with the low voltage signals required by the power train management system without showing any visible corrosion. I would also check the fuel pressure and resistance of the plug wires. Finally, I would have the battery "stress tested" at an auto parts store even if it is fairly new.

See attached.
 

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Discussion Starter #3
Thanks for the documents!!! I'll check the grounds and have the battery load tested. It's about 3 years old, but that's been about as long as I've had the issue. I'm tempted to pay the $150 diagnostic fee at the dealership to see if they find anything. Any idea what type of code check they would need to do above and beyond a regular OBD2 scan? Someone I talked to mentioned they need to subscribe to some kind of diagnostic code service.
 

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As I understand it, the dealer can bring up error codes stored in memory that involve intermittent conditions that have occurred in the past but are no longer present (no check engine light). These are stored for a specific number of operating cycles and dropped if the condition does not recur. Once the codes are located, their definitions and possible remedies are readily available online.
 

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The dealerships all have a Tech2 scanner that is way more than just a code reader. It can do all sorts of diagnostics and allow the tech to view parameters / codes while the engine is running. Of course, troubleshooting an intermittent problem is tough regardless of how good your diagnostic tools are, so they may or may not have any luck finding your problem.

What makes you think it would be the cam or crank position sensor? It seems to me it could be any number of things.
 

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Discussion Starter #6
Unfortunately the issue I'm having doesn't appear to be something that many with the first gen V with the LS6 have so I'm struggling for possible causes that I can try myself before getting put through the ringer by taking it to a dealership. The sensors were suggestions on other threads, but what doesn't make sense to me is the stall only when cranking the wheel left rapidly at high or low speeds. That issue is at least repeatable. The stalling/shudder at cruising speeds does happen if you drive the car long enough. I'm really at a loss. The car is 100% stock with the exception of the shifter.
 

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I would definitely start with darkmans suggestions on his first reply. I could easily see it being a bad ground for the drive train. Have you had the recall done on the fuel pump?
 

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Hmmm, I was wondering about the fuel pump recall, too.

Try going to Stability Control Off and see if it still does it. The left turn stumble could be due to the steering wheel position sensor. And the stumble while cruising could an intermittent Stability Control activation due to a bad sensor. (Over the years I've experienced issues with or seen issues reported with the SWPS, the yaw sensor, and the hubs/wheel speed sensors.) Turning Stability Control off completely would take all of that stuff out of the equation.
 

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Discussion Starter #10
Hmmm, I was wondering about the fuel pump recall, too.

Try going to Stability Control Off and see if it still does it. The left turn stumble could be due to the steering wheel position sensor. And the stumble while cruising could an intermittent Stability Control activation due to a bad sensor. (Over the years I've experienced issues with or seen issues reported with the SWPS, the yaw sensor, and the hubs/wheel speed sensors.) Turning Stability Control off completely would take all of that stuff out of the equation.
The stability control system was the first thing that came to mind when it first happened. I completely shut it off via the controls (didn't pull any fuses or anything) and it the issue persisted. I just had the battery load tested at Auto Zone yesterday and it came back as GOOD. I stopped in to talk to a Service Manager at a Chevy dealership to ask him about his familiarity working with Caddy's, and he said with an issue like mine that I would be better off taking it to the Caddy dealership since the platform is only theirs. He said to expect to pay $1k or so to have a dealership find the issue since it's not throwing any codes. :-(
 

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Yeah this is a pretty tough issue to pinpoint. I was fairly confident it would have been the recall. I would take it to cadillac and see if they can just do a scan on it with one of their Tech2 scanners. They can check for more errors than what an OBD2 scan will show. Looks like you mentioned they would charge $150 for it. If they don't find anything, I might try replacing the ECU? Looks like it goes for about 120$ on Amazon. If it doesn't work, just re-sell it. The reason I mention the ECU is because all other systems run through it and the ECU is able to check that they are functioning. But there isnt much to check if the ECU is damaged. It would be a long shot, but this issue seems pretty obscure and hard to diagnose. You either need to pay cadillac to start diagnosing, or you need to start throwing parts at it, or a little of both. Did you try darkmans suggestions on checking/cleaning grounds? I would also visually inspect every run of wire you can in the engine bay (within reason) and just check for any punctures or cracks in the wire harness cover/electrical wrap. If you find something, check that the wires aren't damaged underneath.
 

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Discussion Starter #12
I think the dealership diagnostic is the next step. I'm leaning towards mice chewing on some wiring somewhere. I just hope it doesn't cost me a fortune to fix. I love my car, but can't afford to let the dealership play the "swap this part out and see if it fixes it" game.
 

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See thats what I'm thinking. Some weird minor wire issue. Don't ever let a shop throw parts at any issue for you (unless its cheap). You can ask for their recommendation, but in this case you can probably do it yourself, if you are handy. You didn't really answer if you had checked/cleaned your grounds yet though, and I'd def look into that. But after you've done as thorough as an inspection as you can at home, take it in for that diagnostic scan.
 

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Discussion Starter #14
I haven't checked the grounds yet, but I will. I'm "Youtube" handy I would say. I just replaced some sensors in my 2001 Audi A4 from a few codes that were being thrown by watching videos online. I'll dig into an issue as long as it's worthwhile. Sometimes the investment in specialized tools and gizmos isn't worth the trouble to possible fix an issue, but other times I'm forced into fixing it myself if the cost to have a repair done isn't in the budget. My worst fixes to date are a heater core replacement on an '85 Mustang GT where the entire dash had to come out and a rear wheel bearing replacement on the Audi. Dealing with old rusty German cars can be a pain. Thanks for the input!
 

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I haven't checked the grounds yet, but I will. I'm "Youtube" handy I would say. I just replaced some sensors in my 2001 Audi A4 from a few codes that were being thrown by watching videos online. I'll dig into an issue as long as it's worthwhile. Sometimes the investment in specialized tools and gizmos isn't worth the trouble to possible fix an issue, but other times I'm forced into fixing it myself if the cost to have a repair done isn't in the budget. My worst fixes to date are a heater core replacement on an '85 Mustang GT where the entire dash had to come out and a rear wheel bearing replacement on the Audi. Dealing with old rusty German cars can be a pain. Thanks for the input!
Good lord haha. Well good luck and let us know what happens. Sounds like youre somewhat confident around a car. Attitude is #1. If you believe you can do it, with enough persistence, you probably can.
 

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Discussion Starter #16
Just thought I'd drop in and give you guys an update. So I dropped the car off at the dealership a few weeks ago. I was pleased to find out they discovered the issue. It turns out that there was rodent damage to the wiring harness to the engine. Finally got things settled with the insurance company, but the subsequent damage to the rear end bushing due to the constant bump starts taking place is coming out of my pocket along with the deductible. I'll just be glad to drive it again and not fear every left turn!
 
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