View Single Post
Old 10-14-2018, 08:30 PM   #7
fdryer
Super Member
fdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond repute
 
fdryer's Avatar
 
Join Date: Jan 2006
Location: NYC
Posts: 43,118
 

2003 L-Series 3.0L Sedan
Default Re: No start, no spark

If you didn't throw away the original crank sensor, you can measure it for resistance with a multimeter. In general, crank sensors will have between 700-1200 ohms. Only two wires will have resistance. A third wire is for shielding the low voltage signals and will not provide any resistance when measuring against one of the two wires. Resistance for good sensors will not vary at ambient temperature, freezing, hot or after rapping it against a table edge. Historical records from many members here in each forum has show intermittent/varying resistance or complete failure (open circuit) in one or several states. Mine changed resistance as engine heat affected it - it failed while driving, became operational after engine cool down and then failed as engine heat forced it fail, the engine dying each time.

Intermittent crank sensors can be tested on a bench by measuring resistance after each test; ambient temps, immersed in boiling water and after rapping it against a table edge several times. Each test replicates the engine environment. Good sensors won't vary resistance by much.

OBD II readers are only as good as the design parameters. It will decode emissions errors with better readers decoding abs codes. General purpose readers will not tell you if an engine computer is faulty except by interpolation - zero communication that may be a blown fuse, damage to wiring between computer and reader or computer failure. Advanced knowledge of electronics helps to determine whether or not engine computers fail. As a rule, engine computers rarely fail.

REWARD EXCELLENCE!

Add to fdryer's Reputation
Rate the quality of this post and help fdryer reputation points. Click the reputation button near the bottom left corner of this message box. Thank you!
fdryer is offline   Reply With Quote