The procedure to replace the Crankshaft Position Sensor (CPS) is below with pictures - you can skip these first sections if you choose, its mostly my ranting.
My Symptoms: Here’s what my car did. The problem started with occasionally taking longer cranking before it would start. Then it sometimes would crank, but not start at all after it had been running (or sometimes start with alot of cranking). I could wait 5 minutes, 30 minutes, an hour, or overnight and it would start – it seemed to be random on when it did it and how long I had to wait. This went on for a couple months, with it happening more severely and more frequently, but still random and intermittent. Then one night after work, it wouldn’t start at lunch. When I went to leave in the evening it still wouldn’t start. I tried disconnecting the battery for 30 minutes, but that didn’t work. Next morning, still no start. Had it towed to the dealer, they replaced the fuel pump ($800!!! I’ll rant about this in a minute). The car ran fine for almost two weeks, and then started the same symptoms. This time it only took a few more weeks before it wouldn’t start at all. This time it was at home. It was getting no spark. I disconnected the battery and charged it and when I reconnected, it started right up. After one day of driving, it again wouldn’t start at home. After checking for fuel (fuel pump was working) and spark (no spark) and trying other stuff, the battery was low. I disconnected the battery and charged it and it started. So I was thinking that disconnecting the battery was resetting something, so I drove it to work. It wouldn’t start – I disconnected the battery for 30 minutes, then an hour, then overnight while charging the battery, and still crank but no start. I had it towed home. I installed a new Crank Position Sensor (CPS) and it started right up and has been fine for almost 2 weeks now. Some other people had there CPS cause the car to die while driving, or go out all of a sudden. Mine apparently was intermittent for several months. And its important to note that it always cranked normally, and the engine light never came on. And when it did start, it always ran perfectly fine – this was the most confusing to me and the reason this dragged on for so long.
About the Cadillac Dealer Shop (a certain, unnamed dealer shop on the north side of Indianapolis...Tutwiler...oh, did I say that out loud?): So from my story above, I had it towed to them and they determined that it was the fuel pump. I asked if they scanned it – they said they had and that it had no codes. I asked how they knew it was the fuel pump – they said that when they hit the fuel tank with a rubber mallet while cranking the car, they could hear the pump spin up for a second. Ok, that sounds reasonable. I took them at their word and coughed up the $800 bucks – I would have attempted this, but my wife was eight and a half months pregnant and I wanted my car to be ready for THE CALL – and I didn’t really have time to mess with it. So I’m sure its possible that the fuel pump and CPS were going out at the exact same time. And the first no start was caused by fuel pump and the subsequent no starts were caused by the CPS – and they just happened to have the exact same intermittent symptoms... yeah, right. OR maybe the dealer just suspected an intermittent pump and threw one on. Even if the pump was bad (and I doubt that it actually was) they still did a poor job diagnosing the problem. The CPS is a common problem on Cateras with these symptoms. The justification for the astronomical labor rates is proper equipment, training and experience to work on Cadillacs. They obviously didn’t have any of this in my case since my problem was mis-diagnosed, or at the very least, incompletely diagnosed (assuming the fuel pump was bad). I thought I was paying for premium service – what I got was royally screwed. Oh, but they do have a “free car wash with service” policy, so I did get my car washed – it only cost me $800. Fantastic. Next time I’ll take my chances with a random mechanic – I may still get screwed, but at least it won’t cost as much.
A quick note about the Service Manuals for anyone that is considering buying them: I’m a novice mechanic, so maybe its just me – but the service manuals don’t seem to be as useful as I thought they would be. The diagrams are often useless – It took me over an hour of looking at the CPS connector diagram and staring at the engine from every possible angle before I found it. And the procedure doesn’t tell you to remove the wiper arms or vent; I don’t see how you could possibly get to the connector without removing them. The index of the manual does not even come close to listing all relevant sections that pertain to the part\term you are looking up. There is alot of very useful info, but its difficult to find and sometimes incomplete.
Crankshaft Position Sensor Replacement
[See picture 1]
The first step is to remove the windshield wiper arms. A tip that I thought of too late: use tape on the windshield to mark the angle at which the arms are attached. Remove the round plastic cap, then the nut from each arm. The arm is wedged onto the cone shaped bolt, so you have to use some force to work it loose. The manual says to - grip the arm with both hands and use a rocking motion - whatever that means. Use some force and pull the arm back and forth in the direction that the windshield wiper would normally move. Eventually it will break loose and move pretty freely. You then have to relieve the tension from the spring-loaded hinge on the arm to be able to lift it off the bolt. You'll figure it out. Make sure to remove the round foam-rubber rings that are under the arms. You don’t want to knock one off and drop it down into the engine compartment and then into a hole in the frame, never to be seen again... not that that happened to me or anything. Tip: use a rag or towel to keep the arm from rubbing/banging against the hood.
[See picture 2]
Next remove the plastic vent cover at the base of the windshield. There are about 5 plastic screws under the rubber seal at the bottom of the windshield. The picture shows one of these screws in the locked position. Rotate the screw 90 degrees to unlock it and it pulls straight out. Use needle nose pliers (or whatever) and pull these screws out - otherwise you'll break half of them when you pull the vent cover off. There's one additional screw on the driver’s side that holds the vent cover to the car body. The driver's side of the vent cover should now be able to be removed - there's about a 2-foot section on the passenger's side that is separate and doesn't have to be removed.
[See picture 3]
With the vent cover removed, you should be able to dig behind the engine and find the CPS connector, but just barely. Look at the picture below.
[See picture 4]
The big connector in the middle was in my way, so I disconnected it and pulled the two ends out of the way. Look at the next picture and you can see the two connector ends pulled out of the way.
[See picture 5]
The CPS sensor is attached to the back of the aluminum bracket In the middle of the picture. It takes a little work to get the clip off the metal bracket, and then get the clip and CPS connector to a position you can unclip them.
If you’re unsure about whether the CPS is the problem, you can try this (I thought of this too late, but you can learn from my mistake). Just drop the new sensor down the back/side of the engine, attach it to the engine, and plug in the new sensor. If the car starts, you can remove the old sensor and route the new sensor along a more permanent route. If it doesn’t start, something else is the problem.
To remove the old sensor, unbolt it from the engine block. The sensor is right next to the oil filter, is sort of egg shaped (round, but wider on one side than the other) and held on by one bolt. If you get the car on jack stands or ramps, you should be able to easily see the oil filter and CPS by getting under the car right behind the driver’s side tire.
An aluminum heat-shield sleeve covers the first section of the CPS wire. The original routing of the wire seems to pinch the sleeve between the oil cooler lines and the engine block. This makes removing the old wire a bit difficult. Here’s what worked for me. Once you pull the sensor off the car, twist the sensor so that the wire twists and breaks free from the heat shield. Then cut the wire at the sensor end. Next, pull the connector end to pull the wire free from the car. I had to twist the connector end as I pulled to get it to come loose. And the shield didn’t come out, just the wire – I don’t lose any sleep over having the empty shield still in there.
[See picture 6]
Next you have to route the new CPS wire. You can see the general path from the stick in the picture. I placed my work light on the top of the engine at the back, then got under the car and looked up to be able to see the general path. From under the car, I ran the stick up the back of the engine and out the top. I then taped one end of a piece of speaker wire (that was a little longer than the CPS wire) to the end of the stick and secured the other end of the wire to the windshield wiper arm. I pulled the stick down and used the speaker wire to figure out my path. Make sure the final path of the CPS wire stays clear of the exhaust manifold – I also tried to avoid the coils as much as possible to minimize signal interference (I don’t know if this is a big deal or not). Then I attached the sensor connector to the wire end under the car and pulled it up and plugged it in. Make sure the CPS wire is routed where you want it and install the sensor and bolt it in. (-Bonus Question: what’s wrong with the picture above – besides the piece of wood sticking out the top of the engine of course?)
Install everything in reverse order – reattach the CPS connector to the clip and attach to the bracket – reconnect the big connector that was in the way – install the vent cover (this can be a bit tricky to get aligned) – install the windshield wiper arms (use the tape marks to line up the arms, or make a rough guess like I had to do) – fire this bad boy up!