How To Repair A Cranckshaft Position Sensor In A 2002 Blazer

HalfDork
12/13/14 vi:08 p.m.

hello all. 02 blazer w/ 4.3, automobile. had a nasty misfire at higher rpms, and threw a p0335 code. so i stopped into a advanced auto and bought a sensor. drive it half manner dwelling and it dies. so i crawl under it and change it in a parking lot. nothing. no spark (verified). i installed one shim, to come across if that would assistance, aught. i walked back and swapped the sensor out for a bwd (10$ more than), and walked dorsum. installed it, both with and without a shim, nothing.

i am pushing it abode (AHHH!), but i need insight. i have power to the sensor, 11.0v, and i verified continuity from each pin to as far back as i can find wires to probe (about 4 inches). id like to check continuity from the plug to the PCM, but i deceit find a pinout for a 02, just up to 96, which appears dissimilar. i verified twice i take no spark. plugs and wires are new, truck ran ok last calendar week.

i institute mention of a relearn procedure, but the steps involve starting the truck and letting it warm upward, which i cant do.

what am i missing?

TL;DR - i need a pinout for a 2002 4.3 blazer, and i need to know what i should meet voltage wise at each of the three wires going to the crank sensor.

-JON

Damaged CKP sensor connector Damaged reluctor ring (missing teeth or non turning due to sheared-off keyway) Sensor output open Sensor output shorted to basis Sensor output shorted to voltage Failed crank sensor Broken timing chugalug Failed PCM

Using a scan tool, bank check if, when engine is running or cranking, that there is an RPM signal. If there is no RPM reading, then visually inspect the crank sensor and connector for whatever damage and repair every bit necessary. If there is no visible damage, and you have access to a scope, yous could check the CKP 5 Volt foursquare moving ridge blueprint. If y'all do not, then, obtain a resistance reading of your creepo sensor from a repair manual. (There are and so many dissimilar types of crank sensors that there'due south no way to put hither which resistance reading is correct). Then check the resistance of the CKP sensor past disconnecting the sensor and measuring resistance of the sensor. (It is best to bank check resistance readings from the PCM connector. This rules out any wiring problems from the outset. Simply it does require some mechanical skill and shouldn't be performed if yous\'re not familiar with automobile electrical systems). Is the sensor within resistance specs? If non, replace the CKP sensor. If so, recheck resistance reading from the PCM connector. Is the reading notwithstanding okay? If not, repair open up or short in the wiring to the crank sensor and re-cheque. If the reading is okay, the problem is intermittent or the PCM may be at fault. Effort reconnecting and checking for RPM bespeak once more. If there is now an RPM signal, wiggle examination the wiring harness to endeavour and induce the mistake.

Read more at: http://www.obd-codes.com/p0335 Copyright © OBD-Codes.com

done all of that^^^

Can you lot verify the sensor was actually bad?

I mean can you be sure the reluctor isn't bad?

Is in that location power to coil?

power to the coil i will check.

i volition also check the reluctor. thanks.

-J0N

i cant actually exam the one-time one, it got pitched at some point by SWMBO.

-J0n

GM connectors can be pretty fragile. I've seen a lot of "bad sensors" that were actually just bad terminals in the connector. Swapping out parts just makes the connectors worse.

In a pinch y'all can Endeavour to tighten the pins upwardly, but y'all might besides exist making things worse if that isn't it.

ok, i accept 12v to the power feed, and verified continuity back to the pcm, pin #12. what is the third wire for?

i have power to the whorl. reluctor ring is intact and spinning. i did notice a slight witness marker from rubbing, then i added the second shim, and tried it, no starting time.

? ahh!

-J0N

xi.0 volts? That sounds very wrong. I'd think a crank sensor would be taking 5 volts, if not that, and so total bombardment voltage. Peradventure you smoked a regulator in the ECU? I'd be verifying what voltage that should exist seeing and checking bus voltages at the ECU.

it is total battery voltage, only the battery is weak cause we've been cranking it. i thought it should exist 5v too...

the other wire is signal return, and the heart one is pcm ground, which i have verified.

i have in one case again heard almost a relearn procedure. is there anywhere i can find such info?

truck is home. nosotros have verified that all three wires are making connection, and other than having 12v instead of the 5v i would expect, everything looks ok.

-J0N

http://my.cardone.com/techdocs/PT%2070-77-0003.pdf

http://www.fullsizechevy.com/forum/general-discussion/functioning/port-injection-96-obd-ii/164702-gm-calculator-relearn-procedure-including-crankshaft-relearn.html

ok, i plant a faulty connector, and twisted the pins on the crank sensor a chip. now i accept rpms in live data while cranking. but information technology still wont first. i cant hear the fuel pump running, and i have no pressure at the rail.

did i screw something upward when i asunder the PCM to probe wires? im certain the plugs are dorsum on correctly and seated.

-J0N

WTH!!!! i have spark now, no codes in the pcm, just no fire. i cant hear pump running. jumping out fuel relay did nothing.

ih8gm!

-J0N

fixed, update later.

Simply to put a cap on something: The creepo relearn is only and then the computer can larn the crankwheel for purposes of misfire detection. Information technology involves bouncing the engine off the rev limiter in one case and letting off rapidly, after yout put the figurer into the testing manner.

So, a lot of the forklifts that I piece of work on use GM vortec 4.3 engines. Only the almost contempo models use cam and crank sensors, but many of the sometime and new style engines have ignition arrangement issues.

What I do when I find no spark, but good power supply and continuity is to supplant the curl and ignition command module. In fact, I ordinarily replace the ICM every bit part of the tune up on machines with questionable Maintenance history. They are cheap as Forklift parts, then they must exist cheaper as auto parts. I've also seen a lot of distributor caps with burnt out center buttons, and so check that advisedly.

FWIW, the 4.three is one of my least favorite engines.

Really interested in the cure hither...

ok, so funny story. the crank sensor probable wasn't bad. neither was replacement #i. #two is certainly skilful. i finally constitute that the connector was boogered. the connector inserts were attached to the wires, and i had continuity back to the ECM, simply it wasn't making contact with the pins on the sensor. i could meet the piddling flap that holds pressure on the sensor pins was either stuck or aptitude dorsum on the 12v+ final. then i twisted the pins well-nigh xxx*, and shoved the connector on, and that'due south when i got spark, and the code disappeared.

but it still wouldn't kickoff. i verified spark at the #1 wire, good blue flame. checked for the lawmaking 3x, gone.

WHAT THE HELL!!!

i noticed after about 20 minutes of messing with it (and kicking information technology and cussing a bit), that i could no longer hear the pump prime...

the fuggin pump died. DURING the diag of no spark, i lost fuel force per unit area. i smacked the lesser of the fuel tank with a hammer, and she fired right upwards. i drove it to my dads shop where we put a pump in it today.

runs bang-up now, and i hate chevys just a little bit more than...at to the lowest degree whe my fords pumps dice, it runs like crap for three weeks, and i know its going. it doesn't simply fail and go out me off stringtown route and I-seventy. (Bowwow).

and then thats my GM story.

-J0N

the only fuel pump i've ever had die was in a 97 Cavalier that had 270,000 miles on information technology, and i was able to drive well-nigh 30 miles home after i figured out that information technology had low fuel force per unit area. it ran like crap from time to time and put me on the side of the road twice, but it fabricated it home somehow. well, i didn't quite get in dwelling house: i made it to within a half a block of my house before the pump finally wheezed it's last breath..

'94 Ford Bronco and a first gen Tiburon both died one me gave me plenty of alarm.

Hyundai was infinitely easier to replace.

The fuel pump in the Malibu went bad and I whacked the tank to go information technology going. I then had the bright idea that since it was running I'd have it 100 miles to my friends shop so I wouldn't have to driblet the tank in my gravel driveway. It died exactly half manner at that place to teach me non to go greedy.

Wally,

funny you say that, the one in my 93 bronco died, and i did the Exact same matter. whacked the tank to get in run, and tried to drive 62 miles dwelling. i got 31 miles. exactly. AAA finished my trip. at least it got me under the maximum l mile free tow i had with AAA, so that was good.

-J0N

novaderrik wrote: the only fuel pump i've ever had die was in a 97 Condescending that had 270,000 miles on it, and i was able to drive almost xxx miles habitation after i figured out that it had depression fuel pressure.

GM CFI systems (anything with the "spider") are very, very finicky about fuel pressure. 5psi off and they won't burn down.

Fought an Astro for two friggin' days (not only me) checking spark and compression and timing and scoping the crank trigger to brand sure it didn't shift somehow and a bunch of other things, and the problem was that it had merely 58psi fuel pressure, which we THOUGHT was enough.

One of those times where learning something makes you feel dumber, you lot know?

yeah. we had about 62 before the pump swap, and it ran, but crappy. no power upward top, no torque. we had 65 afterward the bandy, and it seemed to run similar new.

-J0N

gm pumps can die slowly too.

i had a 3.1 TBI lumina dustbuster van run on 2psi of fuel pressure.

4.3 TBI engines are one of my favorite unkillable machines, 4.3 vortec engines are one of my least favorites.

Source: https://grassrootsmotorsports.com/forum/grm/help-stranded-2002-chevy-blazer-no-start-after-crank-sensor-replacement/96731/page1/

Posted by: hartmuns1953.blogspot.com

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