Cadillac XLR - Cooling Fans run Constantly, Even when Cold - P0128, P0115

howdy folks welcome back I think there's been a mistake this is not a rusted-out municipal plow truck or a crusty old farm tractor it's a 2006 Cadillac XLR she's a mint-condition 50,000 miles on the clock detailed to the nines and for some reason that's in my shop so if you're not familiar with the Cadillac XLR it's basically a Corvette I believe the chassis is the same has the same rear suspension same trans axle setup but it uses the Cadillac Northstar v8 engine instead of the whatever LS v8 you would find in a Corvette and this one has a retractable hardtop I don't know if they all have retractable hardtop Saur not I actually didn't even know it was retractable it looks just like a regular hardtop but yeah I guess it all folds up into the trunk or something all right here's the list on this car I think all the problems are problems that it had before they put it in storage for the winter and then they just got it out so it's only had a few miles on it since it's been out of storage the check engine light comes on sometimes it's actually not on right now so we're gonna look into that see if it's got any history codes the cooling fan sometimes runs all the time and then most recently on the last drive he said that the low coolant light came on and that was during the time that the fan was stuck on I hope I have that right and then the air conditioning needs to be charged I guess the compressor has a little bit of a leak and then you know sitting over winter it just loses all the freon so we're gonna charge that up but these first three issues I'm a little bit more concerned about I don't know if these have the same head gasket problems that the other northstar engines had the earlier ones like the 2000s I think these are quite a bit better but low coolant and the cooling fan running all the time has me a little bit concerned well I hope you guys can read this I don't have any kind of fancy screen recorder setup on the auto tell here this is an auto tell max assist 906 BT by the way a lot of guys asked about that can buy one of these for about a thousand bucks and I recommend it it's been a very good scan tool so it looks like most the code they're gonna be there's a p0 1 to 8 for the coolant temperature below what what the PCM expects and like each module is gonna report back all these codes that get passed back and forth between the different modules so you'll see the same thing repeated over and over again so a p 0 1 1 5 telling us there's a problem in the engine coolant temperature sensor circuit it's got a bunch of weird communication codes in here for the what steering wheel module or something what we're not gonna worry about any of that crap so the two that we care about is a p0 1 to 8 and a p0 1 105 so by the way this is one of the hardest parts I think especially if you're you know kind of new to this is figuring out which of these codes matters and which of these codes you can kind of ignore and I don't have a great you know like silver bullet answer for that but usually history codes that have been cleared aren't that big of a deal and depending on how the monitors are set up the thing will clear its own codes in a lot of cases I mean you look at this car and it's just a it's just an absolute mess of systems so every single one of these is a system that can store its own codes engine control engine cooling engine electrical TPS HVAC parking brake cruise control keyless entry wipers I mean it just goes on and on which is insane doesn't need all this crap anyway let's worry about these two for right now [Music] it's kind of running like Creek a little bit crazy it's pride just because the scan tools plugged in notice that sometimes can make the engine idle strangely anyway let's watch the engine coolant temperatures see what happens here they've been running now for 14 minutes we're only up to 168 degrees and this upper radiator hose is definitely worn [Music] twenty-one minutes in alright with 30 minutes in up to 210 degrees Fahrenheit so that's what almost 100 degrees Celsius anyway I want to see if the fans run and when the fans run if they stay on or do anything kind of weird I'm pretty sure we just have a bad thermostat but I want to be sure all right I don't have you guys a bill to read this through the camera but here's what it says for our p 0 1 to 8 so basically there's some enabling conditions here it's got to be above idle not in fuel cut more than half the time blah blah and it's gonna run a monitor on a 500 millisecond loop under normal driving conditions and that basically says that the computer thinks that the coolant temperature should be at least 195 degrees Fahrenheit but the actual temperature that its measured is less than 161 degrees Fahrenheit for a period of 10 seconds or the temperature hasn't reached 143 degrees Fahrenheit at all it's gonna set that code and I guess there's another one here which must be like a one trip code and I don't know when it chooses which one whatever well that why they don't have two separate codes for this but this one shows that one trip code with some monitoring at the mass airflow sensor and basically just means that the it hasn't reached 167 176 degrees Fahrenheit Adri Celsius during that trip so I feel pretty confident saying that this car has a bad thermostat that the thermostat is sticking open and failing to reach the minimum operating temperature I say we take this pig for a ride I've got some data pulled up here let's see if we can reproduce the symptom of the fan sticking on and yeah it should be pretty fun car to drive well don't live our life a quarter mile at a time alright fantastic fans just kicked on so we've been driving for had in about ten minutes still hasn't gotten above 150 degrees Fahrenheit and the computer just turned on the fans so that's what we wanted to see and I'm tooling right along you know obeying the speed limit and all that jazz so cool we're able to reproduce the problem actually this car right surprisingly well I'm uh I'm very impressed you would think by looking at it that it would ride like a skateboard but it really doesn't ride bad at all all right I just pulled off you can definitely hear the fans running the scan tool says they're going 83% we've been driving for about 12 minutes has not gotten above 150 degrees Fahrenheit that we probably should not take the gravel road though interestingly the cluster now shows it ed well it shows 100 degrees Fahrenheit but the gauge is basically pegged out all the way at zero but the live data still shows 150 degrees so the cluster is still telling us basically zero for temperature the live data says still about 158 we've been driving while it's been running for almost 33 minutes we have not gotten above 158 so that's pretty cool we're able to 100% confirm the customers complaint I'm really glad this wasn't some kind of bizarre intermittent problem anyway I'm gonna run inside and get some parts and we'll get this guy fixed right up pretty weird hop up all right folks this car needs a thermostat and I feel extremely confident that just replacing the thermostat is going to solve all of these issues so just to review we have a p0 one to eight code stored that's engine coolant temperature below regulated temperature the p zero one one five is some kind of generic code I cannot find code setting criteria for that it's actually not even listed as a DTC in the service information for this car but it's some kind of a generic engine coolant temperature sensor circuit fault we know from driving it that the temperature never exceeds one hundred and fifty five degrees Fahrenheit this thing should be you know 190 plus these things like to run pretty hot now we know that the cooling fans come on after let's say about fifteen minutes of driving and then they stay on basically until you turn the car off and the gauge on the cluster shows that the temperature is basically you know what a hundred or it's pegged all the way at its minimum value so what's the deal why would the cooling fan run when the temperature is below you know the regulated temperature it doesn't make any sense well we have to understand how this cooling system works and this is not your granddad's cooling system so I'm gonna explain how it works at least my interpretation of how it works and depending on your disposition you guys are gonna say that's that's quite clever or you're gonna you know mutter under your breath about keeping it simple stupid and how this stuff saw way too complicated and prone to failure anyway inside of the PCM there's a couple things going on but basically this orange line here is the actual feedback from the engine coolant temperature sensor that's what seeing as an input to the PCM and it's about fifty degrees fahrenheit today so about ten degrees Celsius so we start up the car we run for about 15 minutes after fifteen minutes it's reached let's say 140 Fahrenheit somewhere in there maybe about 65 degrees Celsius I apologize if I don't get my Celsius conversions is a pee right it's it's not as I'm not as good with that one as I am with with linear measurements any now this pink line right here represents what the ECM has calculated the engine coolant temperature to be and this is some kind of a proprietary blend of 11 herbs and spices probably based on intake air temperature vehicle speed rpm run time throttle position engine load who knows maybe even fuel trims I have no idea how they calculate this thing but basically the computer knows what engine coolant temperature it should expect to happen at any given time and there's a monitor that runs what was it every 500 milliseconds or something like that anyway so every once in a while the computer is going to compare its expected value to the actual value and it's gonna say hey do we have a problem so what happens is he monitors run and after enough these conditions are met the computer basically makes a judgment call and it says hey we cannot trust the actual engine coolant temperature information that we're getting it's too far off from what we're expecting to see at this given time and I believe what's happening is it's setting this p 0 1 1 5 itself and switching off the gauge in the cluster it's also turning on the cooling fans because it doesn't actually know what the coolant temperature is so it's it's airing on the side of caution and it's turning the fans on to protect the engine in case this number is actually a false reporting and that it's actually lower than what it is so that the computer can't trust what the engine coolant temperature sensor is telling it it assumes worst-case scenario that this thing is smoking hot and it needs to turn the fans on to try to cool to cool the system off so it's basically programmed to failsafe you know the PCM wants to protect the engine doesn't want it to overheat so it it just turns the fans on to be safe and I think that's pretty cool now by the way that's not this is not confined to GM other manufacturers do the same thing I know for sure that outi will do I don't know I haven't run into this problem on other cars but I do know for sure that an Audi will do this pretty much the exact same thing so anyway that's how it works kind of cool I guess or frustrating if you're on the other end of it you know and you could easily go down a rabbit hole with this you know chasing engine coolant temperature sensor circuits and you know fan driver modules and you know throwing a bunch of parts at it thermostats gonna fix this problem I'm pretty confident about that I'm like the junk I usually work on we actually have to be kind of careful with this one so I've gone ahead and prepped the patient [Applause] well I think we could do it with this upper radiator hose in place but it would be a lot easier if we just take it out so I'm gonna take it out hmm well there's your problem lady the thermostat ate itself ain't gonna work like that no sir cool I'm glad we found something makes me feel better yeah you see what happened it's got this rubber boot around the disc here that's your that's your valve basically that opens up and the rubber has come apart it looks like most of it's still there it's just it's just wadded up down here on the bottom so I don't think we need to worry about a bunch of little pieces floating around in fact I'm not gonna worry about it we'll just replace it but yeah interesting failure so our replacement does not have that rubber seems like a quite a bit more robust design okay thermostat housing is cleaned up got a new gasket new thermostat it's gonna go in here like so and then this whole thing's gonna go there underneath the throttle body like that we'll just get rid of this looks like it's just asking to get wound up in a serpentine belt maybe I'll clean that up and throw some electrical tape around it that's better I guess when you jam that much stuff [Applause] the one thing I've found with these constant tension clamps if you can get them back exactly in the same spot where they came off like the same orientation that they came off they usually have the best chance of not leaking well I see why the AC wasn't working she's empty bone-dry it's recovered zero about point zero two anyway ain't gonna work like that the coolant doesn't look very good now this green bucket is why I drained out of the car this metal bucket here is what it should look like it's next cool but it looks really rusty and cloudy so we're getting some new coolant [Music] [Music] [Music] [Music] well I don't know where that vacuum coolant refilling systems been my whole life but that is pretty slick I've only used it a handful of times but it is awesome I had to top it off just a hair but it sucked all the coolant in that it needed and still had a little bit of vacuum left to go that is fantastic very little mess it's better than any other system for filling coolant that I've ever seen okay we're gonna go for a confirmation Joyride but we're looking pretty good it's been running for they ran for a few minutes before this so probably about five minutes we're already up to 156 so we're looking pretty good let's go let's go feed on this thing for a little bit okay folks I think we got it it's holding steady right at 190 fan is off as it should be been running for about 15 minutes the gauge in the cluster is reading just fine that's why I think we got a ripped [Music] looks like this upper radiator hose might have been leaking a little bit it's really not very bad looks good well everything looks pretty good about the Fancy Pants cover put back on topped off the coolant the air conditioning works think we're done under here see anything missed hooked up all the wires are hooked up that's it right books there you go how to fix your 2006 Cadillac XLR when the cooling fans run all the time and the coolant temperature sensor makes no sense I went ahead and cleared the codes out of it we're gonna ship this thing get it out of here before anything bad happens to it is it's way too nice to be around me anyway I hope we get a good video out of this because it's a pretty cool problem and I did not find anything in the service information that tells you that the PCM has this strategy to turn the fans on if it doesn't understand what's going on with the coolant temperature sensor but I know that's the deal as I've seen this happen before so that could easily throw you for a loop and hopefully we get a video that can help people if they have the same problem alright guys thanks for watching this is actually a pretty pretty cool car and he told me that they made GM eight I guess less than eleven thousand these accel ours they're fairly rare you know a lot more rare than a Corvette and I think he told me there's only 40 of them with this particular color combination so that's kind of cool but that's double-edged sword I don't know if you guys ever watch the car wizard but he had a video about a Cadillac X Cadillac XLR and I think it had a bad radiator he was trying to find a radiator for it I guess parts are hard to get for these at least the parts that are specific to these cars the engine parts and parts that are you know common with the Corvette not so hard but apparently the actual unique XLR parts are kind of hard to get

Channel: Watch Wes Work

Views: 53,780

Rating: 4.9659925 out of 5

Keywords: cadillac, xlr, car, fix, mechanic, check engine light, code, p0128, p0115, cooling fan, thermostat, coolant, gauge, weird, running, repair, diagnose, scan, autel, northstar, v8, engine, monitor, drive cycle

Id: IIxR4bGenwU

Length: 23min 4sec (1384 seconds)

Published: Sun May 17 2020