Dealer can't diagnose--Buick LeSabre keeps dying

Hi Cartalk Community,

Has anyone ever had a car keep dying for no reason that can be diagnosed? It’s worse when I’m stopped at a light or coasting at a slow speed, but has happened when throttling up. Once, it started to die while I was keeping a steady 40 mph, then righted itself and kept going.

The dealership’s mechanics can’t puzzle it out because the car will die, but it starts right back up, so they can’t get any diagnostic codes. (It ususally starts back up immediately for me, too, but not alwyas.) They replaced the crank sensor, but that didn’t fix the problem. The next step is to replace the computer, but I’m afraid I’d be throwing good money after bad. Any thoughts are greatly appreciated.

Since the engine controller is very reliable I think you are correct about wasting your money to replace it. That would be one of my last suspects for this trouble. I suppose there are no codes being set to give a clue to the trouble. If you can think of anything that happens just before the engine dies, like any warning lights turning on, it would help to pin the trouble down.

My first suspect would be an electrical problem with the ignition system and then the fuel system. The ignition switch area is another place to look at.

Cougar, the battery icon on the dash lights up right before the car dies, and about half a second later, I just lose power steering and braking along with the acceleration. It’s a peaceful death–no noise or shaking. And it almost always starts right back up.

Even without diagnostic codes, I would think the dealer’s mechanics would have tried the simpler things like ignition switches first if they thought there was even a chance of that being the issue. But then, I know I can’t assume anything.

You did not tell us the model year of this Buick, or whether it is still under warranty.
If it is not under warranty, there is no reason to continue to take it to the dealership, particularly since their diagnostic work has not been effective so far.

Ask friend, neighbors, relatives and co-workers for names of service stations that are both competent and honest. This list should not include any chain operations. A good independent mechanic is at least as capable of fixing this problem as the dealership is, and in many cases will be more capable, as well as lower cost.

Jennifer, I certainly suspect the ignition switch. Turning off with no codes stored in your car’s computer means as far as the car is concerned everything is fine and dandy. Do you have a bunch of stuff on your key ring? A fully loaded key ring can get very heavy and over time it can damage the contacts inside the switch. It seems like the switch is stopping the run signal and going to the ACC “accessory” mode.

When you “restart” the car you move the switch and reestablish the contacts again. I’m not big on replacing parts on a whim, so I’d giggle the ignition switch with the engine running and see if you can make the car die. Or the next time the car is dying just put you hand on the key and see if it comes back. Once you loose your power steering the motor has stopped and needs to be restarted by turning the key.

VDCdriver, it’s a 2003 with < 80,000 miles. It’s not under waranty, though, because it was a salvage (body work, nothing under the hood was involved). I have done my comparison shopping, and the dealer’s quote is comparable to the others. But I have considered taking it elsewhere since the dealer’s guys don’t have any other idea for me.

UncleTurbo, I only have the key, my house key, and the remote lock/unlock device. If that device is the problem, then that would be an easy fix to do without it. I will try your suggestion when I get home. The problem is not consistent, though. I drove it for two hours total last weekend and it was on its best behavior. But then it died in the parking garage on the way to work last Monday morning. (Luckily, that was one of the times it started right back up, so I didn’t make the 50 people behind me late for work.)

I second the recommendation on the key switch. It’s fairly inexpensive and easy to replace.

Didn’t we have a Buick a while ago that died when the owner was turning and a shop owner posted with his own experience? I have a appointment so I will check when I get back.

If it is the PCM,ECM “computer” why not the 8yr 80k Fed warranty on it?

Hey, I am running Windows 7 64-bit Release Candidate and really like it.

The battery warning light turning on may be a good clue Jennifer but it could also just be a result of the engine not running. In order for that light to turn on power has to be provided from the ignition switch so that part of the switch is working at least. I assume that also means power is getting to the ignition area but will have to verify that. This may just mean the ignition switch is ok and the trouble is beyond it.

Cougar, the radio and fan stay on when it dies, too.

oldschool, the warranty is no good because the car was totaled in a previous life and had to have some body work. Not extensive, but costly enough to total it. I believe I am only the third owner of the car though. My Dad was the second owner. (Yes, I got a good deal.)

[Edited to add that I searched for the discussion oldschool refers to two posts upthread, and I can’t find it exactly. A couple of folks have had trouble with turn signals, but that’s not my car’s issue. I’ll keep looking, though.]

Looking at some data for your car it shows an ignition-1 relay that may be causing the trouble since relays are famous for causing this kind of intermittent trouble. One of the things it supplies power to is the cruise control. You could turn it on if there is a power on indicator light and see if that light goes out when the trouble happens. If it does then that relay should be changed out.

The symptoms could point to more than one problem so I’ll throw out few possibilities.

  1. The dying at a stop or low speed could be caused by a dirty/faulty Idle Air Control valve. This is not unheard of at all.
  2. Dying at speed (steady 40 MPH) could be caused by an erratic fuel pump. These can be a hit and miss affair and will not set a code.
  3. The third one is the one I would look at first and that is a faulty/corroded battery cable or junction terminal. All electrical power to the car goes through the cable and the junction terminal and if the connection is poor this means a high resistance in the circuit. High resistance means more heat. This in turn can cause an intermittent failure as the computer can shut down if the system voltage goes below a certain amount due to the high resistance in the circuit.
    This could explain the car dying but yet the radio/fan will either continue to run or pop instantly back on the nano-second the engine dies.

I would thoroughly inspect and clean the battery cables (even under the insulation near the cable end) and clean the junction terminal (very easily done) before spending any money on high priced parts; especially the computer which you likely do not need at all.

Are you saying that the Federal 8yr 80K catalytic converter and ECM warranty can be refused if the car has a salvage title (this is the worst I can think your car has)?

I know this warranty can be refused if maintiance items are ignored.

Here is the “my car dies when hitting pothole post”

Or a better link

According to the dealership, yes, the salvage title voids the warranty. Perhaps I should verify, though.

ok4450, the battery connection is the first thing we checked. Also, we changed the fuel and air filters. Not sure how to check the fuel pump or idle air control valve. But–and here’s one thing I didn’t mention at first–before going to the dealership I took it to a local indie mechanic who has a fantastic reputation (25+ years; I’m told he used to work on the local police car fleet). He spent two hours looking and listening. When nothing looked amiss, and his computer didn’t pick up any codes, he told me to take it to the dealer. He did, however, replace the air and fuel filters for good measure. Does that change the assessment at all?

I saw that, oldschool. But since the turn signal issue isn’t an element of my problem, I didn’t read the whole thread. Now that I have, though, I noticed the ignition switch keeps coming up. But why would the dealer not have tried that?

To Uncleturbo, from upthread: I tried jiggling the keys-- can’t kill it. But it goes rogue on its own timetable.

Thanks to all for weighing in so far. I’ll check in tomorrow to see if there are other ideas as well. It’s much appreciated.

At this point my opinion has not changed.
“Checked the battery connection” means what? A visual?

Assuming the cable end and battery terminals are clean what I’m referring to is the cable underneath the insulation near the cable end. This involves cutting the insulation back some to inspect.
The cable end where it makes contact with the battery post may be spotless but the same may not be said for the cable wire to end connnection.

The junction terminal is near the battery and a visual inspection of this may reveal nothing. It has to be disassembled (easy enough) to inspect and even that can be a judgement call. One’s opinion of the condition may be that it’s fine and someone else may say it’s not.
If the connectors have a gray colored film on them then they’re dirty. This is scale that must be cleaned away.

One of my previous SAABs used a junction terminal much like your car and it looked great and worked with no problems at all until a few minutes after I checked into a hotel while on vacation in Colorado. Walked out and nothing; no start, no idiot lights, etc.
A test light showed the terminal was the problem so about 5 minutes later it was clean and everything ducky.

Without pending or stored codes to get you started in the right direction, I’d suspect that a poor ground or loose connection (possibly chaffed wires from the earlier crash) is causing an intermittent fault. I’d have an assistant try to move and pull / push the wiring harness(es) with the engine running until the stalling can be replicated. Then you’ll have to do some detective work to find where the problems is from there - probably where a harness comes in close contact to the body or an engine mount.

Alternatively, you could have a lock-up torque converter that is failing to disengage, causing the car to buck and stall like a manual transmission car left in high gear. Many GM cars of 1990s -2000-ish have 4pd transmissions with lock-up converters. The symptoms that happen on acceleration might negate this diagnosis, but its possible that the torque converter is not unlocking. You can remove the fuse for the overdrive (you’ll only be cruising around with three forward speeds; it won’t hurt anything, but your gas mileage may be a bit reduced on the highway) and see if the problem goes away. Good luck!

Anything can be intermittent. Intermittent means that 99.9% of the time a component will operate, and test, completely good. You can’t reasonably test it enough times to uncover that 0.1% of failure.
Even battery connections can seem good 99.9% of the time, and, then, fail.
I would sand, scrape, file the battery terminals and the battery posts; or, replace the cables.
The ignition switch is a prime suspect. Can the 0.1% failure period be proven?
And, then, there are the ignition components. They are next on the list.

An intermittent power loss can be for only a few milliseconds, and then, restore. The engine computer, and other electronic devices, can be turned OFF by the momentary power loss, and back ON, in those milliseconds, and not know that the OFF period was unintended. Therefore, they set no trouble codes.
The momentary power loss can occur at any wire, or switch, which supplies power to the affected components.