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P1336 DTC in 1999 GMC Savana 2500: Crankshaft Position Sensor Issue and Fix Guide

Model: GMC Savana 2500 Fault Code: P1336 Posted: 2007-07-05 13:59

I own a 1999 GMC Savana 2500 5.0L cargo van and recently received a P1336 diagnostic trouble code (DTC). After researching, I believe this code relates to the crankshaft position sensor (not 'crank speed fluctuation sensor' as some may assume). The P1336 code specifically indicates 'Crankshaft Position Variation Not Learned,' meaning the engine control module hasn't learned the proper crankshaft position signal during startup. My question is: where exactly is the crankshaft position sensor located on this model? Do I need to remove the oil pan to access it, or can I find it more easily behind the timing cover or balancer? I've already checked all wiring connections related to the crankshaft and they appear intact. The van runs smoothly under normal conditions—no noticeable performance issues—but the service engine light remains on. According to my Actron DTC lookup, a relearn procedure is required to clear this code. However, I'm unsure whether this can be performed with a basic OBD-II scanner or if specialized equipment is needed. Additionally, after replacing spark plugs and wires as part of a tune-up, the code disappeared temporarily—though it may return under certain conditions. Can anyone confirm that a standard tune-up resolves P1336 in this vehicle? Or does this point to a deeper sensor or timing issue?

Related fault codes
P1336
Comments (11)
Anonymous 2007-07-05 15:57

CSF is likely a misnomer—correct term is crankshaft position sensor. The code P1336 refers to the engine control module not learning the crankshaft position signal during startup.

Anonymous 2007-07-06 06:53

Yes, P1336 = Crankshaft Position Variation Not Learned. This typically occurs when the sensor is faulty or the system fails to establish a proper baseline during engine start-up. A relearn procedure is required to resolve it.

Anonymous 2007-07-06 08:10

The crankshaft position sensor on a 1999 GMC Savana 2500 is typically located behind the timing cover, not under the oil pan. While a service manual would confirm exact location, removing the oil pan is unnecessary and not required for access.

Anonymous 2007-07-06 09:06

I've confirmed that the van runs smoothly without any noticeable misfires or performance issues. All wiring to the crankshaft appears intact. The P1336 code persists despite normal operation—this suggests it may be related to sensor signal learning rather than a mechanical failure.

Anonymous 2007-07-06 09:24

My Actron DTC lookup confirms: P1336 = Crankshaft Position Variation Not Learned. This is a common issue in older 5.0L engines where the ECU fails to learn the correct crank position during initial startup.

Anonymous 2007-07-06 09:47

Thanks for clarifying! What does 'not learned' mean exactly? How do I perform the relearn procedure, and what tools or equipment are needed?

Anonymous 2007-07-06 10:43

A proper OBD-II scanner with a relearn function is required. The process usually involves cycling the engine through startup, idle, and warm-up phases while the scanner monitors the crankshaft position signal to re-establish learning.

Anonymous 2007-07-06 10:56

This assumes the sensor itself is functioning correctly. If the sensor is faulty or has intermittent contact, a relearn may not resolve the issue long-term.

Anonymous 2007-07-09 07:24

Thanks to everyone for the help! After replacing spark plugs and wires as part of a tune-up, the P1336 code and service light disappeared—though I’m not sure if this was a temporary fix or if it will return.

Anonymous 2007-07-09 10:33

A tune-up can resolve P1336 in some cases because misfires during startup may interfere with the sensor signal learning. However, if the engine runs smoothly and no misfire is detected, a faulty sensor or wiring issue should be investigated further.

Anonymous 2007-07-09 13:19

Interestingly, even though there were no audible signs of misfiring, the code appeared—suggesting that the ECU may detect subtle signal inconsistencies not noticeable through sound alone.