failed smog code 1345 CKP sensor chilton book

[renno]

My 96 sierra failed smog do to code 1345 on the self functional test.
I've run the CKP tests according to the chilton book and the sensor fails when I hook up the test light between terminals A & B. It states to repair the CKP harness ground circuit (terminal B). It doesn't give any other info. on how this is done. What am I looking to do here. I just bought the truck because the engine had been recently rebuilt.

Also the CKP wiring diagram in the book shows the two outside wires as being pink & purple with yellow in the center. The CKP wiring harness on my truck has the pink and yellow wires on the outside & purple in the center. Is this a misprint or is the harness wired wrong. Any help on this would be appreciated.

Thanks

[Jeremy-WI]

P1345 is CKP/CMP correlation error. It may be caused by a bad sensor, but most likely caused by attempting to change timing by turning the distributor, incorrectly installed distributor, jumped/stretched timing chain, or possibly distributor gear wear. A scan tool is needed to adjust the distributor on the V8 5.0, 5.7, and 7.4L engines as of model year 96. If you recently replaced the intake manifold gasket, it could be a tooth off on the distributor gear, or distributor just needs turned to get the cam retard(CKP/CMP offset) as viewed on a scantool to 0 degrees +/- 2 degrees. Chilton's book got the wire colors right, not the location of them in the connector.
Does the truck seem to run fine or does it have a little hesitation or miss above 45 mph steady cruise or when getting on the accelerator going up a hill or towing?

[tnvolz]

Originally Posted by Jeremy-WI

P1345 is CKP/CMP correlation error. It may be caused by a bad sensor, but most likely caused by attempting to change timing by turning the distributor, incorrectly installed distributor, jumped/stretched timing chain, or possibly distributor gear wear. A scan tool is needed to adjust the distributor on the V8 5.0, 5.7, and 7.4L engines as of model year 96. If you recently replaced the intake manifold gasket, it could be a tooth off on the distributor gear, or distributor just needs turned to get the cam retard(CKP/CMP offset) as viewed on a scantool to 0 degrees +/- 2 degrees. Chilton's book got the wire colors right, not the location of them in the connector.
Does the truck seem to run fine or does it have a little hesitation or miss above 45 mph steady cruise or when getting on the accelerator going up a hill or towing?

Mine does hesitate/stutter when getting on the accelerator (particularly up a hill). 1345 code, distributor shaft not moved, CKP sensor replacement tested and this is not it. Is this distributor gear wear ?
Thanks

[Jeremy-WI]

Get it on a good OBD2 scan tool and have the cam retard checked. Distributor gear wear usually results in a misfire at light load cruise

[tnvolz]

Originally Posted by Jeremy-WI

Get it on a good OBD2 scan tool and have the cam retard checked. Distributor gear wear usually results in a misfire at light load cruise

Thanks for the reply.
Removed distributor and the gear was worn almost to a "knife edge"
on the gears. Truck ran fine, mileage fine, but SES light always on. Replaced using the reman. distrib. (new gear has blunt edge on teeth). Installed new distrib., cleared OBDII codes and now SES light is out.

However, hesitation remains, typically under the uphill/acceleration conditions (no load other than driver) you mentioned earlier in post.
It will "surge" and then even out. Typically am seeing this in/at 2nd-3rd shift.

Truck has 160K miles (probably lots of hwy.) and I believe original drivetrain.

Am uncertain as to whether to chase :
a) cam retard as you suggest or
b) throttle or
c) transmission
Will cam retard setting range always throw codes and then SES light?

Thanks for any input !

[Jeremy-WI]

Cam retard can be out of spec enough to cause misfires even without setting a code/SES. You can get the distributor pretty close by getting the engine to TDC of the compression stroke of cylinder #1 and then remove the distributor cap, the rotor should be pointing to a "v" shaped pointer cast into the side of the distributor base with a 8 on it, if it doesn't line up, loosen hold down clamp and turn distributor so that it does line up
http://www.mhtc.net/~jbomkamp/distributor.jpg

[tnvolz]

http://www.mhtc.net/~jbomkamp/distributor.jpg[/quote]

Thanks for the pic, I'll check (4.3LV6 motor in this truck - 99 model).
When I tried to move the distributor before replacing it, It appeared to not be moveable (maybe I'm missing something here...) and/or had a stationary position that the hold-down bolt keeps it in.

My understanding was that the distributor goes into the correct tooth position and the engine control computer trims to optimum??? (and correspondingly if the tooth was one off, that the trim range wasn't enough to reach optimum)...and that essentially, with the distributor replaced, the SES light would indicate if the tooth position put you into the range that the computer could trim out to...

Thanks again.

[Jeremy-WI]

If its a 4.3 the rotor should line up with a 6 on the "v" shaped pointer and the distributor is not adjustable on most of them. The cam retard spec is +/- 15 or 20 degrees too. I think some people have had luck eliminating misfires on the 4.3 by using a distributor cap with brass contacts and there were some issues with a A/C line that is above the cap that has a tendency to drip water onto the cap itself- it is usually remedied by adding an insulating sleeve on the A/C line