GM 3400 Crank Shaft Position Sensor B Quick and Easy Way to Replace

[@artemc329]

This video is for sensor B - engine has 2 crankshaft sensors. Sensor A is located behind the crankshaft pulley at the front of the engine. Check description for link to video guide for sensor A replacement.

[@thorthunder3227]

I know how to replace it but my problem is where do i find the harness wire? I seem not to have one for the crank.

[@jeromebland8287]

I just leaned over the hood and reached my hand behind the engine with 1/4 ratchet and got it and replaced it. I literally did one on Thursday at the shop I work at

[@josephtrunk3565]

I have to replace this sensor on my 94 Ciera 3.1 liter. No error codes have shown up, but another owner of this exact vehicle did the same thing I did, thinking they had a bad fuel pump, which took out the fuel pump relay, installed new relay, new fuel pump, as well as the fuel sending unit, fuel filter, fuel rail fuel pressure regulator, and engine still stalls after about 12 to 15 minutes of driving , and will not restart until it cools off. Changing sensor tomorrow, hope it fixes the issue, will let you know. Thanks for sharing!

[@artemc329]

If it doesn’t fix the issue, you may have to re calibrate the sensor using an advanced scan tool

[@josephtrunk3565]

@@artemc329Thanks for your guidance on this. The 119 degree heat index weather today curtailed my getting much done with it. But I did notice the crank sensor and its pigtail connection has oil and coolant all over it. Likely, this has been slowly building up to becoming the stalling and intermittent problem connection due to the coolant and oil invasion.

[@bgjobass]

@@artemc329Hi, I got the rear crank sensor replaced today, 6/10. I went from the top of motor mid point, which was very doable with the removed upper motor mount, and pulled the motor forward. By using a facial mirror, I was able to see the pigtail connector and sensor, remove them, and replace pigtail connector and sensor. A lot easier to do being able to see with the mirror. Engine started easier than I remember. Next, I turned Ciera off and on several times, over a few hours time period, it start easily each time. Next up, I need to put more protective dirt and heat shield material covering on, in order to keep new pigtail connector from getting soiled again. Thanks again for your assistance.

[@artemc329]

@@bgjobass good work - it’s always a good feeling when you solve the problem. You saved yourself around $300-400 by doing this yourself as this is how much shops in my area charge for this job.

[@bgjobass]

@@artemc329 thanks, always a good feeling to do it yourself and save. Especially when it makes your old, favorite car, that was your dad’s last ever, run well once more.

[@egoldie22]

Thanks for your effort and please post more for the impala if you still have it because I have the 02 and I still can’t get it started 🙄 all advise is welcome and appreciated!

[@artemc329]

Best way to start with this issue is to pull the codes. Most cheap scanners will work. Then you should bring the codes to autozone and have them search the database. It is free and they own the repair databases that all auto shops use to find the correct fix.

[@pe00100]

Thanks for putting this video together. I took my engine out and thanks to this video and all the comments found out about crank position sensor B. I’m having a hard time finding where to connect it. Could someone give me a ball park location? Is the only sensor that is left where I can’t find where to connect, now I at least know what it is.

[@artemc329]

there is a wire that runs from the ignition control module to the crank sensor B. The coil packs sit right on top of the ignition module. The wire should come from the driver side of the module

[@lemonpunchGamer]

How did you get your hands down that hole I’m having a lot of trouble trying to get any of my tools to the sensor, I can’t take off my passenger side wheel right now it’s snowing hard in my state and gotta get my car off the road or at least running to avoid tickets but u can’t reach the sensor at all or the bolt holding it in, is there shit I can take off my engine on that side to make it easier to get at? The only thing I can do right now is the intake hose and that’s not much more space for where I need it, and how could you tell you were on the right bolt when you got the tool down there?

[@cyperuslive]

You ever figure it out? I’ve gotten the bolt off the sensor but damn am I struggling to get it off

[@kingketes264]

Question, i dont have any codes or problems with crank but i do have a small oil leak coming from what looks like this sensor. Because theres no oil above it and my oil pan doesnt look leaky either, the stream looks like it comes directly from this sensor. Is it possible for it to leak? Also would i need to drain oil to change it? I have a 1996 buick century and this is the only video i could find of anyone even aknowledging the fact of there even being a sensor behind the motor. I have the 3.1 3100 v6 almost the same but sensor looks just like that

[@artemc329]

It is possible that the O ring that seals sensor to the block could have become old and leaked. Take a paper towel and run it across where you suspect the leak to start. Work your way from the top of the engine down. If you get fresh oil on it - there is your leak. Be sure to find the source of the oil leak first before throwing parts and money into it. As you know, accurate diagnosis is the most important part of fixing a problem. For advanced diagnosis, you may dye the oil with UV dye and use a UV light to find the source of your leak. You would not need to drain the oil to replace any sensors in this engine, nor the valve cover gasket. Be sure to get an OEM AC delco sensor if you choose to replace it. Vital components such as timing sensors could leave you stranded if defective. OEM is twice the price but you won't need to do the job twice due to defects. I would even go as far as buying an aftermarket sensor, removing the new O ring and applying it to my old factory sensor if I had no choice.

[@thorthunder3227]

I have a sensor under my harmonic balancer and one in the side of the block. Does these 3.4L have both sensors for the crankshaft?

[@artemc329]

Yes, the 3.4 has both of the sensors you are describing. P0335 is the one by firewall, and p0336 is behind the harmonic balancer

[@thorthunder3227]

@@artemc329 Thanks I was wondering how they worked together to impart the right timing sequence. I cannot seem to find the one plug off my 2002 grand am but found the block side one and plugged it. I have no idea where the other sensor wire is.

[@artemc329]

@@thorthunder3227 if you are referring to the sensor behind the crank pulley, the wire is held in place with a bracket and can be very hard to see. It is routed between the engine block and AC compressor. I am not entirely sure why GM put 2 sensors in. You would think it was for redundancy but the car will not run if either of the sensors go bad, so that wouldn't make sense.

[@thorthunder3227]

@@artemc329 Found out someone cut the three wires off the sensor, the other sensor has two wires going to the could pack area and i assume that is the ICM?

[@artemc329]

@@thorthunder3227 Yes, the module that sits under the coil pack is the ignition module

[@NSander8]

The connector that goes into the crankshaft position sensors on the back side of the engine is a length of wire that plugs into something else. Do you have any idea where the other end may plug into?

[@artemc329]

The wire that runs from the crank sensor (near firewall) plugs into the driver side of the ignition control module. This is the part that seats the ignition coils which the spark plug wires attach to.

[@NSander8]

@@artemc329 Thanks man. One more thing, on the upper intake to the left of the “3” in “3400” there is a vacuum hole going into the upper intake. I don’t know what goes there so I currently have a vacuum cap on it but what is supposed to go there and what does the other end connect to?

[@artemc329]

@@NSander8 the way you have it is correct - the small hole you are referring to is supposed to be capped from the factory.

[@thorthunder3227]

Where does that sensor wire hook to after you have it on the sensor. Does it hook to the coil pack? Do both sensors hook to the could pack? I guess what i meant to say does the two sensor wires link to the coil pack on each end of the pack?

[@artemc329]

The sensor near the firewall connects to the module that sits right under the coil packs on the driver side of the module. The other sensor behind the crank pulley connects to the pigtail near the AC compressor which is part of the engine wiring harness. I am not certain where the wires lead after that since they are bundled with the rest of the wiring harness.

[@thorthunder3227]

@@artemc329 I found them and someone cut the three wires off in the haness. I will have to try to trace them out and find out if they have continuity to the ecm. On the coil pack end there is the female that has a male end that plugs into the coil but whan i traced them down the wire went to the 10 amp fuse and connected over to the yellow hot wire of the switch and i assme that 12 volts should be read there but i get only .05 at the male end of the plug that goes into the coil female on the coil pack. Should i have 12 volts there and if not what could be the problem, swich connectors or wires?

[@artemc329]

@@thorthunder3227 Sensors should never have 12v running through them as far as I understand. The 0.5v you are getting should be correct. Sounds like someone really messed up the wiring harness. If I were you, I would buy a used harness from eBay to save myself the headache of tracing wires and checking voltage. I think it will save you a lot of time going this route.

[@robertoj5679]

Is there a good camshaft replacement video for this?

[@artemc329]

I am sure there is something out there. If I was replacing the cam, I would pull the engine out and reseal everything and replace all wearable parts while it is out of the car. It’s fairly easy to pull the engine and get to the cam in this engine without specialty tools

[@robertoj5679]

@@artemc329 oops I meant to say the cam position sensor but your videos on the other sensors are the best I've seen thnk you

[@idrewzy7645]

I don’t know if mine is A or B I’m starting with A but I haven’t been able to get the pulley bolt off what’s the easiest way to remove the pulley bolt without an impact I’ve tried a wrench but it’s just way to tight

[@artemc329]

An OBD2 scanner will tell you whether it is sensor A or B. You could try a breaker bar but most likely you will just spin the engine over and risk breaking the bolt inside the crankshaft - at which point you will create a lot of work for yourself. You could use a hand impact wrench (which work very well with pulleys) if you really had no way of setting up pneumatic or don't have an electric one. You could also try placing a wrench on the bolt, then hammer the wrench in the direction that will loosen the bolt (this will work like an impact wrench). Either way, impact function is very important because it delivers quick light blows rather than constant torque preventing the engine from turning over and placing less stress on the bolt. As last resort measure, you could apply heat to the crankshaft pulley bolt which will heat up the crankshaft, and after a few minutes of heat spray the bolt with water. This will cause the bolt to contract while the crankshaft expands making it easier to remove. This will cause damage to the front main oil seal and has potential to cause other issues, so only use this method as last resort to prevent bolt from snapping in the crankshaft.

[@arnoldramos39]

Great video thanks 👍

[@Josh_D03]

Question. Did your car show rpm when the sensor went bad? I just drove my car 100 miles yesterday now today cranks but no start and its not showing any rpm when cranking

[@Josh_D03]

Trying to get an obd reader here today

[@artemc329]

this car does not have an RPM gauge - only fuel, speedometer and temp oddly. Usually RPM will not start showing up until the car has started, and the starter stops spinning (to save power and send as much of it as possible to the starter). However, if you were getting strange RPM readings before the car refused to start - it is likely the crank sensor since this is what measures engine RPM. OBD scanner will be your best diagnostic tool in this case.

[@franka-pn7wi]

not easy reach thanks show youtube smile

[@DanielWalsh-w6z]

Why don't u just disconnect the battery for 15 seconds that will reset your lights

[@MVMTV4Videos]

try

[@Whimsik]

Absolutely miserable explanation