Loss of Communication Codes

[Poobah]

I've driven my 2000 Deville about 3000 miles. During that time, the engine has occasionally bucked, or acted like it just stopped running for a brief fraction of a second, then continued running as if nothing had happened. I've also gotten an occasional U1016 Loss of Communication Code. There seemed to be no correlation between the bucks and the code, I've never gotten a plug misfire or engine stall code, and the check engine light never came on.

This weekend, during a 300 mile trip, the engine bucked rather severely and the check engine light came on. The engine ran flawlessly for the next 125 miles until we got home. I pulled the codes and got the following (all history):

IPC U1000 Class 2 Communication Malfunction

IPM U1016 Loss of Class 2 Communication with VCM

IRC U1016 Loss of Class 2 Communication with PCM

SDM U1040 Loss of Class 2 Communication with ABS

PCM P0385 Crankshaft Position (CKP) Sensor B Circuit

I know from reading this forum that Loss of Communication codes tend to be caused by battery and grounding problems. The old battery died a few weeks ago and I had it replaced. About a week ago, I inspected the battery and ground connections under the rear seat cushion and found them all to be clean, tight, and as new in appearance.

There are computers and ground connections all over this car. Any idea where I should start looking?

Thanks in advance.

[MAC]

The first thing I would do is make sure the battery cables are free of corrosion and there is a secure connection. I had a similar problem and I traced it to corroded cables.

[JimD]

I've driven my 2000 Deville about 3000 miles. During that time, the engine has occasionally bucked, or acted like it just stopped running for a brief fraction of a second, then continued running as if nothing had happened.....

PCM P0385 Crankshaft Position (CKP) Sensor B Circuit

There is your clue. You might try exercising the connectors on both sensors before you start replacing parts.

[Poobah]

Jim D,

Thanks for the suggestion. If the crankshaft sensors on a 2000 are in the same places as they were on the '94 (front, center, above and below the half case seal) they are a little hard to reach unless I can get the car up on a hoist. I read somewhere on this forum that it's a good idea to put something like electrolytic grease in underbody electrical connectors to keet out dirt and corrosion and to improve electrical contact. Would it make sense to put some on the crankshaft sensor connections?

Mac,

VERY nice looking Eldo - especially given its age and mileage! I used to have a '94 Eldo with 160,000 mi. but it didn't look nearly as straight as yours.

[JimD]

Jim D,

Thanks for the suggestion. If the crankshaft sensors on a 2000 are in the same places as they were on the '94 (front, center, above and below the half case seal) they are a little hard to reach unless I can get the car up on a hoist. I read somewhere on this forum that it's a good idea to put something like electrolytic grease in underbody electrical connectors to keet out dirt and corrosion and to improve electrical contact. Would it make sense to put some on the crankshaft sensor connections?

I have done the job on ramps. Remove the oil filter and the oil filter adapter to make room for your hands and arms.

Also, I would leave the air deflector off for a fews days just in case the sensor is indeed failed or failing.

I am an advocate of using the appropriate grease of compound if only to preclude any moisture wicking its way in there.