2003 Cadillac CTS shuts off after 20min and starts up after 30min cool down

[lrod25]

Ok, I recently had problems with my 2003 CTS. At first I would be driving and it would just shut off, no warning at all, it would turn right back on with no problem at all. Now it turns on perfectly fine but after about 25min it shuts off, again with no warning. This time it won't turn on for about another 30min or so. It seems like something gets hot which causes it to shut off and then when it cools down it works fine. Last week I had some relays replaced because the cooling fans were not turning on, that didn't change anything. I plug it to the DTC computer and it was calling out for the rear driverside O2 sensor. That didn't change anything and it's still calling out the same DTC. Can the O2 sensors cause the car to shut off? My other concern is that a mechanic came by and told me that it might be my ignition coil, I'm not sure about this cause I was told that your ignition coils are either good or bad, there's no in between. I really need to figure out what's causing my car to shut off.

[Marlin]

I was told that your ignition coils are either good or bad, there's no in between.

VERY wrong. I have seen planty of cars in my old shop where the coils either got weak or started to go bad.


But I have not worked on the 3.2L. Does it not have a coil for each cyl? If so i doubt its the coils as they would ALL not go bad like that at the same time. I might think coil if you said it loses power and the compurter says 1 of the cyl has a miss.


When it shuts off have the traced it to fuel or spark?
Spray soem carb cleaner down the throttle body and try to start. If it does then shuts off you have a fuel problem. If not test for spark. If no spark from more then 1 coil then trace back from there.

[lrod25]

Thanks for the fast reply! The CTS has two ignition coils (left/right bank). I don't get any messages from the computer about any cylinders missing. We checked the fuel pressure and that all checked out good. The problem I'm having is figuring out how to check for spark. Here's another problem I noticed today, the coolant outlet hose looks like it's clogged or something because it calapsed (as if squeezed it together) It doesn't feel like water is flowing through it. I guessing this is another problem, maybe the thermostat. Do you think it's the thermostat? Could this cause the engine to shut down? How can I check for spark?

[urbanski]

crank position sensor?

[Sammy Z]

I don't think you can check these cars for a spark. Your problem may be related to what they did with the relays. Or, I'll also suggest Crank Shaft position sensor. My engine would spin but not start when hot, I changed that sensor and it fixed the problem.

[Marlin]

You can check for spark but it is not as easy as some other cars.


What you do is take 1 of the coil packs off. You will need to have spark plugs plugged into the the 3 coils. Take a wire and wrap around the threads of the spark plugs and hook the wire to a ground on the car. Make sure you hold the coil pack facing down, plugs will face toward the engine not the sky.

Have someone try to start while you hold the copil pack and watch for spark. If you see no spark then you know where to check. If you have spark then plug back in and try to start. If still no start spray the carb cleaner into the throttle body and see what that does etc...


Also try posting this querstion at a Saab forum since the 3.2L is a big version of the 3.0L motor. Being the CTS only used the 3.2L as its major motor for one year you might get more ideas at a Saab forum. The trick abovbe about checking for spark is what the saab owners do with their cars. I use to have a 900SE before I got the CTS.


Saab forums I use to post at.
http://www.saabcentral.com/forums/index.php

[redbanditcts]

im having the same problem on my 2003 cts. it also seems that the transmission goes on some kind of manuel mode...i was in the parking lot when my computer said it was powering down the car...

[bburt]

I go with SammyZ on checking the crankshaft sensor first. It messes up a lot of things when it goes, and it can be intermittant. In my case it went out in the midst of morning rush hour and I was in the fast lane when it quit without notice. That was not fun! I don't know how hard it is to check it on your own - I suspect you need a diagnostic unit. A good shop can do it in a couple of hours and check out other possibilities as well. I've been told that these sensors are a real pain, but great moneymakers for auto shops, because they're not too time consuming to replace and so many of them go out.. Just had one go out on our Nissan. Both have a little over 50,000 miles on them.

[MomsCady]

I had the same problem and it was the crankshaft sensor. Ask them to check this. Good luck