Electrical issues?

2012 NISSAN MICRA
127,000 MILES • 1.4L • 4 CYL • TURBO • 2WD • MANUAL
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NOTSTEVE
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Car Issue Summary (Nissan Micra Diesel 2012)

Hi, I need help diagnosing a strange electrical issue with my 2012 Nissan Micra XV Diesel.

Symptoms (only after 40+ mins of driving):

Speedometer suddenly goes crazy, then stops working

Key warning light appears on the dash

Steering becomes light like EPS is off

Car jerks while accelerating/decelerating

Car doesn’t shut off unless I hold the stop/start button for long

One time after bump-starting (without ignition ON), car didn’t start for a few mins

Airbag light is always on

Error code related to rail pressure stored


What I’ve Noticed:

Problem only happens after long drives

No parts like ECM, alternator, or battery have ever been replaced

Idle engine load is ~45%, rail pressure ~220 bar


What I’ve Done:

Checked fuses visually

Checked battery:
Engine Off-12.69v
On-14.25v
On Load like ac,radio,headlights,etc-14.05v


Any ideas on what might be causing this? Could it be ECM, IPDM, grounding issue, or something else?

Thanks in advance!
May 21, 2025 at 11:55 AM
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STRAILER
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Hello,

Yes, you are on the right track, I have seen the IPDM cause these kinds of issues but before replacing it I would do a CAN scan, here is video which will show you how:

https://youtu.be/u-4syLc-ifQ

If the IPDM is bad there should be codes giving us confirmation if the issue.




May 22, 2025 at 11:48 AM
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NOTSTEVE
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Need Help Diagnosing Electrical Issue - 2012 Nissan Micra XV Diesel

Symptoms:

After ~40 minutes of driving, speedometer drops to 0 while driving

Power steering becomes extremely light (no resistance)

Key warning light appears on dash

Car starts jerking during throttle changes

Car won’t turn off unless I hold the stop/start button for a few seconds

Fault Codes (when issue appears):

B2629-00 Vehicle Speed
B2615-00 BCM
C1606-01 - EPS Motor

What I’ve done so far:

Battery,ipdm and alternator checked — working fine


After heating up, the issue returns exactly the same

If cooled down and restarted, all works normally again


Main Question:
Is this more likely to be the Vehicle Speed Sensor (VSS) or the BCM (Body Control Module) failing when hot?
Any tips for diagnosing or testing further?

Thanks!
Jun 1, 2025 at 1:17 PM
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STRAILER
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These codes are the main problems, but I would replace (or have tested) the BCM first in case it fixes the other codes as well. I have also seen the instrument cluster go out and back feed into the BCM as well, did this car have water damage?

B2615-00 BCM
C1606-01 - EPS Motor

Here is the BCM location, also a bad ground car cause this as well, here is a guide to help test the connections and the wiring diagrams as well. Check the fuse again for the BCM as well.

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

Check out the images (below). Please let us know what happens.

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Jun 2, 2025 at 10:28 AM