Code P0385 Crankshaft Position B?

Tiny
JOSH_019
  • MEMBER
  • 1996 FORD BRONCO
  • 5.8L
  • V8
  • 4WD
  • AUTOMATIC
  • 265,000 MILES
Hi, I’ve been having trouble with a P0385 - Crankshaft Position B sensor check engine light. I understand that sensor is really just a “misfire sensor” and I was having some misfires on cylinders 4 and 7 but nothing too crazy. I’ve recently replaced all the spark plugs and wires, ignition coil, ICM (with OEM Motorcraft from Ford) and it has a WAI distributor I put in around 4-5 years ago. New oxygen sensors as well. I tested the compression to rule out any mechanical issues and all 8 cylinders were around 110-120psi. After testing compression, the misfires on my reader went away and while that seemed promising, I’m still immediately getting a p0385 pending (after clearing codes) and shortly followed by the check engine light. I’ve also recently (2 years appx) replaced the crankshaft sensor with an OEM Motorcraft part. I also had the harmonic balancer re machined and balanced and put in the original one back in after getting cleaned up. None of these have fixed the P0385. I’ve checked the resistance from ICM to PCM on the IMD wire and got 0.3ohms. The fuel trims seem to be normal as well and nothing else jumps out on the freeze frame or live data. I’m not sure which direction to go next. Thanks for the help.
Tuesday, July 15th, 2025 AT 6:38 PM

16 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
Hi,

It sounds like you may have a short to power if the light turns on right away. It could be a short to ground as well, or even a wire broken internally, causing too much resistance in the wire or not having continuity at all times.

I attached the diagnostics below. It sounds like you have already done some of the procedures. Take a look through them and let me know if there is anything there that is helpful.

Take care,

Joe

See pics below. Note: If you look at pic 2 below, you will see I highlighted one of the tests that is not listed. If you feel that is the direction you need to go, let me know.
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Tuesday, July 15th, 2025 AT 8:30 PM
Tiny
JOSH_019
  • MEMBER
  • 11 POSTS
Okay, when I get back home, I’ll try the test from the sensor to the PCM. I was able to test the voltage by back probing on the sensor while cranking and I was getting the proper voltage if that changes anything.

Also, when I do the tests you sent, I do not have a breakout box... Can I still test the resistance and continuity without installing a breakout box?

And just to clarify when I reset the light it doesn’t come on “right away” I can run it and idle and the scanner will pick up a pending code then after I turn the car off and on a few times, it’ll eventually come back on with the “confirmed code”. If that changes anything.

Is it possible that a bad distributor is the cause or does this also?

Thanks
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Tuesday, July 15th, 2025 AT 9:11 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 54,137 POSTS
Yes, if the distributor is bad, it can cause this code, also if the timing chain is worn out it will cause "slop" in the timing pattern which will cause this code as well. But the most obvious problem can be the wiring.

DTC P0385 - Crankshaft Position Sensor B Circuit Malfunction

Here is a guide to help with that and the engine wiring diagrams below to help as well.

https://www.2carpros.com/articles/how-to-check-wiring

If the wiring is good replace the distributor. There is a chance the PCM is bad as well FYI. Check out the images (below). Let us know how it goes.
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Thursday, July 17th, 2025 AT 9:52 AM
Tiny
JOSH_019
  • MEMBER
  • 11 POSTS
Ok so here is what I found with wire tests:

On DK2 when I reset the code the MIL doesn’t immediately illuminate but I do get the pending code and I get the code on the key on engine running test.

On DK5 the signal wire to pin 51is good continuity with resistance of.5 ohms but the return was on pin 6 of the harness not pin 91 but the resistance was also less than 0.5. But no continuity to any other pins on the PCM. Not sure if that’s an issue or the diagram is maybe wrong?

No shorts noted on DK6
DK7 all those showed OL so I believe that’s good nothing touching in the PCM.

On DK9 I backprobed the pins from the sensor and at idle I got 0.5 volts and with increased throttle it went up to about 1 volt. Not sure if I’m reading the flowchart as that’s good or bad?

DK10 is good - it’s a newer sensor and the tone ring/harmonic balancer have already been replaced.

All the connections look clean and free of debris or oil.

So should I try distributor now or does anything in those tests stick out?

Thanks
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Saturday, July 19th, 2025 AT 10:46 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 54,137 POSTS
Sorry, I forgot to tell you you need to have the PCM and distributor unplugged to test the wiring.
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Sunday, July 20th, 2025 AT 10:00 AM
Tiny
JOSH_019
  • MEMBER
  • 11 POSTS
Ok the PCM was unplugged and key off but distributor was still plugged in. Do I need to disconnect the wiring harness on distributor?

And just to confirm if I do again and I don’t get any continuity between the MD sensor return and Pin 91 and only to pin 6 then that is no good correct? Should I try a jumper and see if that clears the code?
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Sunday, July 20th, 2025 AT 10:44 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 54,137 POSTS
Yes, the wiring must be disconnected to test it, yep give the jumper a try to see what happens.
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Sunday, July 20th, 2025 AT 10:47 AM
Tiny
JOSH_019
  • MEMBER
  • 11 POSTS
Ok so the MD sensor is a black yellow wire which the same as pin 6. The 91 should be grey red but I don’t see that ever going to the MD sensor. I just wanna make sure pin 91 is correct. One of the wiring diagrams shows pin 6 as the MD return on circuit 651. I don’t want to fry anything jumping to pin 91 if it should be 6.

Also same results with the distributor disconnected.
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Tuesday, July 22nd, 2025 AT 12:56 PM
Tiny
JOSH_019
  • MEMBER
  • 11 POSTS
This also shows misfire sensor as pins 59 and 6
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Tuesday, July 22nd, 2025 AT 1:13 PM
Tiny
JOSH_019
  • MEMBER
  • 11 POSTS
I also just tested that pin 91 and it seems like it’s a return for the sensors which concurs with the Chilton page wiring diagram I sent
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Tuesday, July 22nd, 2025 AT 1:25 PM
Tiny
JOSH_019
  • MEMBER
  • 11 POSTS
Sorry for the multiple messages - I also pulled the current MD sensor and resistance is good on that sensor and I’m getting good AC voltage back to the PCM. And when I clear the code and I do the key on engine running test it picks up the code on the first attempt. Not sure if that helps us diagnose at all.

Josh
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Tuesday, July 22nd, 2025 AT 4:07 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 54,137 POSTS
This is a strange problem, it seems like everything is working the way it should but I have seen a bad PCM cause a problem like this. If all of the wiring seems good from the distributor and misfire sensor I would try another PCM. Also, the compression seems low I have seem extremely worn timing chains cause codes like this as well.
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Wednesday, July 23rd, 2025 AT 9:41 AM
Tiny
JOSH_019
  • MEMBER
  • 11 POSTS
Ok so should I try the PCM and distributor first? Or what would you try next?
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Wednesday, July 23rd, 2025 AT 10:32 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 54,137 POSTS
I would try the distributor first, this part is more likely to fail.
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Wednesday, July 23rd, 2025 AT 1:26 PM
Tiny
JOSH_019
  • MEMBER
  • 11 POSTS
Ok I replaced the distributor same results on KOER shows the P0385. I even ran new wires from the MD sensor to the PCM and they’re getting between 0.3-1.3 VAC while doing that KOER test...I’m stumped
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Wednesday, July 23rd, 2025 AT 2:41 PM
Tiny
JOSH_019
  • MEMBER
  • 11 POSTS
I’m going to pull the ECM and check to see if any capacitors are blown - difficult to find a new one but I think I can take to an electronic repair and have it recapped. I guess it’s down to that or the timing chain you mentioned. Although the car seemed to run smoother with the PIP Spout connector off when I was timing it so perhaps it is a PCM problem
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Thursday, July 24th, 2025 AT 2:42 PM

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