: 1996 Sedan Deville Knock Sensor

06-29-04, 12:16 AM
I have a service emissions coming across the DIC and my service engine light stays on as well. I have had a scanner put on my car and the code coming up is P0325 which indicates Knock sensor circuit. Does any one know if this indicates the sensor is bad or is it the wiring? Also is the code P0325 the reason why the service emissions light is coming on? I have a Chilton's repair manual and it doesn't tell much. I can't even locate the sensor in the car, all I know is that it is in the center, upper enigine area, mounted in the rear of the intake manifold. Has anyone replaced a knock sensor or can someone please help and if possible send pics? Thanks....

06-29-04, 10:04 AM
You've discovered why Chiltons manuals are generally regarded as next to useless....

The knock sensor is under the intake manifold in the valley of the engine. There are no coolant passages in the intake manifold so it is easy to take the 10 mounting bolts out and lift the manifold up to access the knock sensor (and starter which is under there, too.)

Likely it is the knock sensor. Nothing would likely have happened to the wiring unless something casued corrosion at the connector to the knock sensor or something like that.

The knock sensor code is turning on the service engine light.

06-29-04, 07:37 PM
I was able to replace the knock sensor, put the intake back toghether and the service engine soon light is still on. Does this mean it is the wiring? I looked at the connector that plugs into the KS and it did not look like it was fried. At this point I'm guessing to check the near end side the connects to the PCM. Any one have any other ideas?

06-29-04, 08:50 PM
The SES light will stay on until the PCM gets 3 ignition cycles without a fault being detected, then the light will gop out and the code will go into history for 50 ignition cycles after which it will be cleared. OR You can clear it yourself.

06-29-04, 11:36 PM
I cleared the DTC (P0325) via an auto zone scanner and the SES light and service emissions system light came back on immediately. Any other suggestions?

06-30-04, 10:36 AM
Check the codes again with that same code scanner if you still have it and tell us what comes up. Somebody will be able to answer. If you don't have the scanner, hold down the OFF and WARMER (or passenger-side WARMER in some cases) buttons at the same time for about 4 seconds to bring up the DIC diagnostics. That will show you the codes. Tell us all of the codes and whether they're CURRENT or HISTORY. The codes will come up on the dash display like this:


Give us the code meaning if you can. One way or another, there are some knowledgeable people here who will probably be able to tell you what's wrong and how to fix it.

You didn't accidentally put diesel fuel in the tank, did you? (kidding) No bananas or potatoes in the tailpipe? (I prefer potatoes)

Happy code reading!

Michael Cowden

06-30-04, 10:42 AM
I believe that the knock sensor code just looks at a resistence at the sensor to insure the connection continuity.....not positive without the service manual....but... begs the question....was the replacement sensor an OEM sensor ?? If not, the sensor might not match the correct resistence for the OCM code.

Disconnect the battery negative cable for 30 seconds to send the code to history to see if that will reset it. I don't know about resetting or clearing codes with the aftermarket scan tools.

06-30-04, 07:47 PM
No the knock sensor was not an OEM sensor. It was an aftermarket sensor by BWD Automotive Corporation and indicates NIEHOFF on the box, I purchased it from Checker auto parts. I do not have the scanner as I have been taking it to auto zone to check the codes and have them cleared. However when this issue first came about I was informed by AMMCO Trans. that the knock sensor code was showing after they scanned the car for both the transmission side and the enigine side. I cleared the codes by taking off the negative batttery for 15 minutes and below are the codes coming up by holding down the off and warmer buttons (thks mcowden, didn't know this). As soon as I started the car after reconnecting the battery the Service engine and service emissions light came on. I also just failed emmisions today because of the SES light which they indicated was caused by P0325 and P0327. I have 30 days to fix it without being charged a late registration fee and to bring it back to them for a recheck with no charge. Any one know why PCM? is coming up while checking codes?:suspense:

No ACM, SDM, RSS codes
PC0325 Current - Knock Sensor Module Circuit
PC0603 History - PCM Memory reset (Control Module Long Term Memory Reset)
IP1552 History
TC0037 History
PZ1558 History
IR2255 History
RF2560 Current

Also before disconnecting the battery I ran the codes and they were the same as listed above with the exception of PC0603 was not present and PC0327 was present (Knock Sensor circuit low input {bank 1 or single sensor}).

07-01-04, 10:32 AM
You're getting there! I'm glad you were able to see the codes with the OFF-WARMER trick. Now, after the codes are displayed and you see "PCM?" up there, you can scroll through various options in each category and clear the codes selectively without the use of any scanners. Use the "fan speed up" key as if it meant "Yes" or "ENTER." Use the "fan speed down" key as if it meant "No" or "Next." Use the OFF key as if it meant "Esc" or "Back." So, when you see "PCM?" you can do this:

<fan up>
<fan up>
<fan up>


<fan down>
<fan down>
and on through the list of categories

Hopefully that makes sense. If you hit OFF a few times, it will back out to displaying all the codes, then the display test, and the next time you hit it you will get back to normal dash display. Play around a little bit to learn the navigation and I'm sure you'll pick it up pretty quickly. Just don't change anything in the OVERRIDES, INPUTS, or OUTPUTS sections. (you'll know what they are when you see them) Save yourself the trips back and forth to AutoZone or wherever to use the scanner.

OK, so outside of that little lesson, it looks and sounds like the knock sensor may have another problem. Perhaps the wiring got pinched, rubbed, or cut somewhere along the route or the new knock sensor doesn't have the same electrical resistance as the original. If possible, I would get an OEM knock sensor, maybe from a Cadillac dealer, and install that one and carefully inspect the wiring.

The other codes in there may not be worth worrying about if you don't have any other driveability problems or concerns. If you want, though, I'll look them up and let you know. I spent the money on the factory service manuals from Helm and they have all the codes. On the 1996 model year cars, the codes they display don't exactly match up with what you'll find online. The two-letter prefix throws things off a bit. Standard OBD-II codes would just say P0325 instead of PC0325, and I'm not sure if all of the numbers match up but the ones I've seen so far do.

Hopefully that gets you somewhere. Let us know how it goes. Good luck!

Michael Cowden

07-01-04, 12:05 PM
I would get an OEM knock sensor......no guarantee at all that the aftermarket part will not continue to set the code. The system was not tested nor developed with that aftermarket sensor so YOU are doing the testing for them....good luck. Replace the sensor with an OEM part before you pull your hair out.

07-02-04, 11:36 AM
Ok I'm getting ready to tackle this again this morning as I have purchased a new knock sensor from GM. I have only one question; I have a multi meter and I need to know how to verify that the wiring is good to the PCM. Not really sure of how to do this, can any one help?:welcome:

07-02-04, 04:07 PM
I have installed the new KS and still the Service emissions system and Servie engine soon light came on. I did clear the codes by disconnecting negative battery and also by using the method provided by Mcowden. I clear code PC0325 and it pops right back up. I did examine the wire to the KS and it looked fine. Upon reading the Chilton's manual I found that it connects to the PCM. I was able to look at the PCM but not extensivly as I did not want to take the connector off the module. The connector did seems as though it was snug on the PCM. Any one have any further ideas before taking it to the dealer? Or if any one knows a good mechanic in the metro Phoenix, AZ area, please advise.:confused:

07-02-04, 05:51 PM
Someone correct me if I am wrong but I am looking at a '97 service manual and as I read it P0325 indicates KS module or PCM fault. P0326 indicates KS or circuit faults. Take a look again at the PCM. You should see a small cover plate on the top (maybe bottom) held in place by 2 screws. Remove that and under it you will find the KS module. Remove it by squeezing the 2 tabs together. That may be your problem rather than the KS itself.

07-02-04, 10:27 PM
I did have the PCM replaced by a tranny shop after they rebuilt my tranny and after that I started having this PC0325 problem. I also read in the Chilton's manual that when you replace a PCM you need to take out the old KS module out and place it into the new PCM. I'm wondering if they did not even transfer the KS module and there is none in there. I'm not even sure what a KS module looks like, can you send a picture if you have one? angel.garcia@attws.com If you can't can you describe the module? Thanks...

07-02-04, 11:11 PM
I did have the PCM replaced by a tranny shop after they rebuilt my tranny and after that I started having this PC0325 problem.......

I always love it when the WHOLE story comes out. You never mentioned this in the beginning...just that you had the knock sensor code all of a sudden...like it came out of the blue.

Mentioning the PCM saga might have saved you some time and work replacing the knock sensor......

Unplug the PCM connectors and check for bent pins. Sounds like they bent a pin connecting the wires from the knock sensor to the PCM at the PCM connector when the PCM was replaced......

07-02-04, 11:16 PM
I am not very good at scanning and sending this stuff but I could have my daughter help me if needed. It should not be neccassary though. As I stated in the previous post pull the PCM again. The service manual didn't say it it was top or bottom but that should be irrelavent when you see it. The is a small square flat cover screwed on to the center of the PCM with 2 screws. Remove the 2 screws and the KS module is under it. It is removed by squeezing 2 tabs together. If you remove it and there is just an empty hole, the trans shop still has your KS module.

07-02-04, 11:27 PM
If you look at the PCM connectors find the clear connector C2. The knock sensor input lead is on pin 62 . it is circuit 496 and is a dark blue wire. Do a continuity check from the PCM connector to the knock sensor with a VOM on that lead.

If the continuity of the knock sensor circuit is OK then replace the knock sensor module in the PCM. It is under the little trap door that has two screws in it. Take the screws out, squeeze the tabs on the knock sensor module connector together and lift it out.

With the above new info the knock sensor was probably fine all along. Wondered about that as they rarely , if ever, fail.

07-03-04, 12:59 AM
My mistake of not giving all the details upfront, I'm new to this forum and I'll know for next time. I'm going to again try this in the morning. But I do have a few concerns. Does tacking off the connector to the PCM remove it's programed memory? I know when the tranny shop replaced it they sent it to the dealership to have it programed. Or is this a case when the PCM is programed it can be connected and disconnected without hjaving to reprogram it. One other question, what happens if the KS module is missing and I can't get it back from the tranny shop as it has been about 2 weeks? Can I but a new one from some where? http://www.cadillacforums.com/forums/images/icons/icon11.gif

07-03-04, 01:11 AM
Taking the connectors off the PCM will not cause a problem at all. Once the PCM is flashed with the calibration and code it does not hurt it to take the connectors off. Disconnect the negative battery cable before taking the PCM connectors off to ensure that there is no sort of power up or down problem but beyond that bit of caution there is really no harm at all in taking the connectors loose.

You can buy a new knock sensor module at the Cadillac dealer.....

07-03-04, 02:44 PM
Ok, just to verify again, I just took the square cover off the PCM that was held by 2 screws. I lifted it up and there was 8 pins sticking up with nothing connected to it. From what I understand the KS module should be pluged into that, correct?

07-03-04, 03:50 PM
That's it exactly. Either contact the transmission shop that butchered your baby and get it back from whatever they took out or get a new one from a dealership or www.gmpartsdirect.com (http://www.gmpartsdirect.com). That should take care of it once and for all.


Michael Cowden

07-03-04, 08:47 PM
Yup, sounds like your K/S module is AWOL. I would ask (insist) that the tranny shop pay for a replacement if they don't have yours.

07-05-04, 12:15 AM
1st off thanks to all for helping to find the problem with the DTC PC0325. But now I have a another issue with my cady. It started yesterday, that when I put the key into the ignition all the lights on the DIC turned on but the car would not start, I tried again and nothing, then third time it started. I checked the battery cables and they were fitted tight. The same thing happened this morning while tring to start the car. Then later in the afternoon while driving the DIC showed (Theft system problem car may not restart). I reset the codes by both disconnecting the battery cables and by clearing the codes via the off and warmer buttons procedure and the codes popped back up. The codes showing are IP2710 and IP2711, I'm wondering if when I removed the intake manifold that I did not connect a sensor back up. My problem is that I checked them already but am not sure which specific one to look at if any. :banghead:

07-05-04, 06:16 PM
B2710 - PASSKey Open/Shorted Pellet
B2711 - PASSKey Open/Shorted Pellet After good key
Check your key. Make sure the resistor pellet contacts are clean. Check to see that they have not worn down level with the pellet. Put a DVM on the pellet contacts and make sure you have continuity and are getting a resistance reading. You may just need a new key.

07-05-04, 07:55 PM
I just had the tranny shop put in the KS module and the PC0325 code cleared.

Now again to the issue with the Theft system problem. I have two keys and I did clean both of them along with cleaning the key ignition itself with electronic cleaner. Both keys do have metal prongs on each side of the pellet they are a bit worn but they do stick out furhter that the black pellet. I did put a Fluke mulitmeter on each side of the contacts and received no continuity on either key. However I'm not sure I'm checking it properly with the meter. To verify my setting are correct I set it to autorange 40 ohms and put the red cable at one end of the wire and put the black cable at the other end and I heard a long beep. I did the same with the pellet contacts and got nothing. After cleaning the keys I started the car, cleared the codes and restarted. I Did this 3 times for each key seperately and the code IP2711 comes up not as current but as history after clearing the code at each ignition cylce. This is very strange as the theft system problem only appears off and on and shows no pattern. So my questions are did I check the continuity correctly and if not what meter setting should they be? Also could both keys have gone bad at the same time? :hmm:

07-05-04, 09:19 PM
I forget exactly what setting I used for the ohms. To check the continuity, put one probe on each contact (left side & right side) and you should get a tone. If it turns out you need keys (can't beleive they could both go bad together) contact Marc at link below. He has them for 5$ (aftermarket) 7$ (OEM). I could not get the site to work but there is a phone no.
You will need to get the resistor value (ohms) before you order.

07-05-04, 09:37 PM
I receive no tone when putting the probes on each side of the contact and set the meter to autorange. When I set the meter to Ohms, one key showed 11.54 K Ohms and the other showed 11.79 K Ohms. Where can I find the resistor value for the keys?

07-06-04, 03:50 AM
Angel, who is the tranny shop? In case I consider going there...

07-06-04, 10:23 AM
I receive no tone when putting the probes on each side of the contact and set the meter to autorange. When I set the meter to Ohms, one key showed 11.54 K Ohms and the other showed 11.79 K Ohms. Where can I find the resistor value for the keys?

What do you mean?? The resistor value is the 12 ohms that you measured. When you have new keys cut they will duplicate the key code on the key blank and use a blank with a 12 ohm resistor.....

If you think it is the keys just go to a Cadillac dealer with your VIN and proof of ownership and they can cut you keys from the VIN without your old keys.

07-06-04, 04:32 PM
402 ohms (acceptable range 386-438)
523 ohms (acceptable range 502-564)
681 ohms (acceptable range 650-728)
887 ohms (acceptable range 850-942)
1130 ohms (acceptable range 1085-1195)
1470 ohms (acceptable range 1411-1549)
1870 ohms (acceptable range 1795-1965)
2370 ohms (acceptable range 2275-2485
3010 ohms (acceptable range 2890-3150)
3740 ohms (acceptable range 3590-3910)
4750 ohms (acceptable range 4560-4960)
6040 ohms (acceptable range 5798-6302)
7500 ohms (acceptable range 7200-7820)
9530 ohms (acceptable range 9149-9931)
11800 ohms (acceptable range 11328-12292)

07-06-04, 06:03 PM
AAMCO on Main St. & Higley. I am going to request a new key and see what happens from there, thxs all...

07-13-04, 12:31 PM
Once again BOBO you are a stud buddy. You should not recommend replacing any parts until you have collected all the pertinent data. That shite is diagnosis 101 baby. Thats the difference between an engineer and a MASTER TECHNICIAN.

07-13-04, 12:35 PM
Here is some advice from someone who really knows! You need a new ignition cylinder and keys my brother. To inspect disassemble the steering column to the ignition cylinder. There are two white wires attached to the cylinder one is most likely broken. If thats the case replace the cylinder and keys. Even if it is not myself I would replace those items. It will save you a tow in the future.

07-13-04, 12:55 PM
I went to a local lock smith and he advised me that the keys appeared good, but he would cut me a new one if I wanted one. He also advised me that he had just had a cadillac brought to him a few months prior to me and it had the same Theft system probelm. He said he cut a new key then replaced the ignition and the problem was still there so the guy took it to the dealership. Knowing this he said it may be best to take it in. Again, the problem is happening with both of my keys and now it is taking longer for the car to start. The DIC shows starting disabled remove ignition key. I do so then try again. It is now taking up to 8 times to start the vehicle and a new code is appearing IP2515, any other ideas?

Also, over this weekend I drove out of town for approximately 90 miles with the air on high driving uphill for about 20 miles again with the air on high. I know I should not have had the air on but having sleeping kids in the car and it being over 110 degrees I did. I then received a msg on my display transmission hot with an alarm sounding off in the car. I checked the codes and PC0218 was the only code. I just had the trasmission rebuilt, my question is; should the car be able to handle this driving without having the transmission hot come on? 2 other freinds in their cars following me had no problem with their car and they had their air on high as well; a 94 Camery w/85,000 miles and a 00 accord w/150,000. I called the transmission shop and left them a msg advising them of this issue on Sat. and to call me and I have not heard back from them. I did notice after having run the car low on transmission for over two weeks but before the trans. rebuild that when I drove the car for a few hours in town non stop with the air on the transmission hot comes on, I 'm going to test it today as well. Again, is their still a tranny problem, should I take it in, or is this normal?:bonkers:

07-14-04, 12:38 PM
Once again BOBO you are a stud buddy. You should not recommend replacing any parts until you have collected all the pertinent data. That shite is diagnosis 101 baby. Thats the difference between an engineer and a MASTER TECHNICIAN.

Keep personal attacks out of the public forums MT. Especially considering the number of people Bbob's expertise has helped.

(Is still having a bad week, so this warning is probably a bit harsh, but I can't think of more diplomatic.)

07-14-04, 11:48 PM
Once again BOBO you are a stud buddy. You should not recommend replacing any parts until you have collected all the pertinent data. That shite is diagnosis 101 baby. Thats the difference between an engineer and a MASTER TECHNICIAN.

What exactly are you talking about....??? Just curious...

If you mean the part about replacing the knock sensor then you must not have read the entire thread.... There were some obvious facts missing ... the part where the poster "forgot" to mention that his problem started after the trans shop replaced the PCM. It was orignally posted as if the knock sensor code suddenly set...and his original question was how to replace it....

He didn't give all the facts and didn't exactly ask for a complete diagnosis of the "problem"

You are really grasping at straws to try and demonstrate some sort of superiority here. I'd rather not get into a pissing contest with you over minor things like that. It would be better for the posters and folks needing help if we could pool our collective resources and answer the questions and evaluate the problems from the engineering and practical sides. But, if you want to engage in a pissing contest, I'm game.....LOL LOL

07-19-04, 12:20 PM
Thanks for every ones help. But no one at this stage has replied back to my last post with the questions I have asked. Can someone please assist, thanks...

07-19-04, 03:44 PM
If you're having start problems with BOTH keys, and the symptoms are the same for both, it sounds like an ignition cylinder more than the key, but before you do anything else, answer this:

Did this problem also start after the butcher shop that pilfered your knock sensor module got finished with your transmission work? If they screwed up more stuff with the PCM, it's possible that could be related to this problem, but someone else can probably provide more details than I can. I don't know much about the PCM's exact functions in this regard.

Now, about the transmission hot stuff: I don't think that should happen. I've driven in mountainous terrain during hot weather with the A/C on many times without any problems whatsoever. It really sounds to me like the "shop" that "fixed" your transmission. They need to know you're having these problems. Your description is not very clear. Are you saying that the tranny was low on fluid for two weeks? Why was it low? Was that before or after the "rebuild?" Ask the shop what exactly they did during the "rebuild." It sounds to me like they screwed something else up because there should be no transmission hot warnings after driving in mountainous territory or in stop-and-go city traffic.

Good luck...

Michael Cowden

07-20-04, 01:55 PM
Yes, the ignition problem started after I removed the intake manifold the second time to replace the KS. I'm not sure if did not connect something back on right or what. Should I have the ignition cylinder replaced by the locksmith even though another caddy had the same problem and it did not solve it?

I took the car back to the tranny shop because of the transmission hot message and no codes were found by them because I cleared them. They just advised me to bring it back if it came back. Problem is only way to make it appear is to drive car for over 2 hours, I guess I'm gonna have to do it....

07-20-04, 05:42 PM
these are the codes that have been poping up, are these all related to the theft system problem (ignition)?