Found out something today regarding this elusive gremlin of a problem with random intermittent stalling and starting problems hopefully it helps people dealing with this issue with there buick. First off my names keith i am a automotive technician at a independent automotive repair shop that specializes in imports mostly european and japanese makes but we pretty much work on everything even the occasional masarati. Im accredited but not ase certified and i have 10 years experience in the automotive repair industry doing diagnostics and R&R work.
Here is my experience dealing with time vampire of a issue on my mothers 2007 buick lucerne . Symptoms were the car would stall intermittently and would crank and not start or start and run rough and have issues staying running . So i agreed to look at the car and have spent around 2 weeks doing different tests to confirm and condemn what the issue is and repair it accordingly like a professional technician would and not just throw parts at it making educated guesses.
I took my moms car to work and it took 3 days before the symptom even happened the car stalled on me then had trouble starting but no codes were thrown so i drove it around with a
scan tool hooked up recording live data of course it would not stall again and everything looked fine on sensors and live data so i stopped doing that after 3 days of driving . I tested fuel pressure it was fine right at 50 psi 55 psi on run. Swapped out the fuel pump relay with one of the door lock relays and hit the lock switch to determine if it was the fuel pump relay it worked fine tested the relay with a dvom meter tested fine .
Cleaned the mass airflow sensor and throttle body then looked at the data and what the throttle position sensor was reading all tested fine within range . Did a tb relearn and a crank and cam relearn using the
scan tool car ran better but i could not get it to duplicate stalling again so i returned the car to my mom told her i did not have any issues and to drive the car 2 days go by she calls said it did it again at her work in the parking lot and the car would not start like the battery was dead but she could not give me accurate info on if the car would turn over or not anyways she said she had to jumpstart the car.
So i take it again of course run more tests . Tested the battery and charging voltage all test fine even though the charge voltage looked a little low at 13.8 volts she said it stalled out after hitting a couple bumps so i suspected the ignition tumbler or contact switch in the ignition due to the recall gm had . Ordered a aftermarket dorman tumbler pinned it out to her key drove it for 3 days no issue gave it back and told her to keep any weight off the key car ran great for 2 weeks then boom again so i take the car. Look at fuel trim and drive it nothing until 3rd day car stalls on me afternoon im also in arizona and it in 111 degree heat she also mentioned it seemed to do it on hotter days. So i suspected a failing alternator but could not confirm it.
It still tested fine so back to the drawing board looked at the TSBs on the car looked at the forums noticed that gm put a winshield washer fluid heating coil that caused this cars battery to drain when it was first sold they had to do a firmware update for. Well we live in arizona so yea pointless to have so i pulled the 60 amp fuse for the system retested the battery voltage and charge voltage and alternator tested fine even better battery went from 12.32 to 12.54 on core voltage and from 13.78 to 13.99 on charge voltage . Suspected the alternator was failing and was not maintaining a magnetic field on hot days but could not confirm it and its a $200 alternator so swapping it on a guess is out of the question and tests were fine car seemed better unplugging that system . .
Drove it for a couple days car ran great . Keep in mind my mother replaced the ignition module on this before i looked at it and i did some much needed service because the car needed it and my moms pretty good on keeping up on service. Did a coolant flush removed the orange dexcool and put in universal yellow. Yea i know gm recomends dexcool i dont care from my experience every gm car ive owned if i flushed and put regular antifreeze or universal yellow or had the money universal red later down the road i would not have LIM gaskets fail or have to change out the head gaskets or the heater core so i do this on all gm vehicles ive owned and recomend it .
Not to mention dexcool oxidizes into a brown sludge from a little air exposure . I recomend this from personal experience . Flushed the brake system . Flushed powersteering fluid and changed fluid due to gm vehicles having issues stalling from the powersteering pumps failing or fluid breaking down putting more of a load on the motor ect ect. Anyways riding with my mother today the car stalls while shes driving wont start at all so i push the car out of the road try it nothing and the lights on the dash go completly out when trying to start it. Which that was a new symptom to me .
So other then spending time figuring out where the starter relay is i just did a hard reset on the car by disconnecting the battery and de energizing the systems its hot out and was not exactly sure if it was security related or what but it gave me the info where to look anyways hook the battery up car starts right up so i get home start looking at the electrical diagram and i notice that it has two relays that control starting the car R3 relay which is just your standard 4 prong relay which btw my mother already replaced and would not explained the surging and stalling issue but looking at the electrical system R6 relay would explain it if the relay was weak or sticking due to sending power to parts of the motor to have the car run.
So i pulled out R6 micro relay notice its a standard 4 prong relay and think WTF gm really? And honestly this makes no sense for any reason to me other then a engineering to fail standpoint so people take the thing to the dealership and have there techs not figure it out and rack up the bill hey my thats opinion. Why i think that is most of the relays in the fusebox exept 3 of them are normal relays . Does not make sense from a money saving or even space saving stand point and then to have this control important systems to the engine and be one of the three micro relays only sense it makes is its engineered that way and not only that so you cant pinpoint the problem right away so people throw parts at there car. not to mention its not a common relay just sitting on store shelves .
Changed it out car runs fine tested the old relay ohm test is barely in range limits which expains why heat may cause it to fail going to run it with the new micro relay will give a update if the car acts up again so no news is good news so to speak my advice is even though i dont recomend throwing parts is to change out the R6 relay in the fuse box under the hood unless you have the means and knowledge to test the relay its a $15 dollar part so if your going to start throwing parts at the car start with that .
If you have a
scan tool look at the live data and learn how to read it first if you can scan tools are cheap and getting cheaper you can go down to walmart now and buy a hypertough bluetooth
scan tool for $50 that works with any android phone its a rebadged
scan tool made by autel. not to mention get 1 manufactures package for free so you can even pull dealer codes for many cars even code transponder keys for some i use this personally and even use it at work so i dont have to wait for the main
scan tool at work if someone else is using it and i dont want to use our old mk808
scan tool that needs a new battery plus i can do pretty much everything with my ap200 autel scantool that the mk808 can
its only $50 but worth every penny walmart should have them listed as the HT200 or HT500 best money for your dollar if you have a android phone you can scan do what most professional techs can . My cost so far other then a ton of time and tests being a professional technician would be around $100 for a updated ignition tumbler that did not fix the issue but in my opinion was a good update due to the recall and design gm used. A $15 micro relay and fluids used to service the car not to mention plugs that the car needed anyways . That was my issue will share any update if the car acts up again also going to pull specs for this micro relay and see if there is a normal 4 prong relay that can be used then make a adapter for it why gm did this makes no sense other then a engineered to fail standpoint in my opinion
