The Nissan Path

when driving in the snow in 4x4 mode, i have experienced the rpms drop for just a fraction of a second, then bounce right back to original level regardless of the speed. this occurs as rare as once every few mins to as often as several times within a minute. i do not recall this happening during the summer when i drove in 4x4 mode on a few occasions, though i am not 100% certain. i will attempt in the next day or so to drive in the 2wd mode while the snow is still on the ground to possibly eliminate the some of the drive mode/road condition permutations.

i have found similar posts throughout the web without anyone identifying a clear solution. here are some of what i found:

1) perhaps too much snow was sucked up into the air intake and clogged the air filter.
2) tachometer locks and unlocks which is supposedly normal
3) try driving with overdrive off (dont like that solution)
4) turn off vcd (REALLY dont like that solution)

i performed a scan using BlueDriver and noticed two codes within (what i assume is a related) ALL MODE ALL WHEEL DRIVE / 4-WHEEL DRIVE category:
1) P1808 Vehicle speed sensor - ABS
2) U1000 CAN communication circuit
hope this helps in some way

to summarize, i have been driving this very Pathy for the last fifteen years in the same part of the country known for its cold and snowy winters, yet i have not experienced this behavior until the last two winters. its is very unnerving having the car jerk in this manner while driving during snow storms, so any suggestions would be greatly appreciated! thanks!

Going by the two codes you found, it could very well be an indication that the ABS actuator/control unit assembly is failing, which is not uncommon on these vehicles. It could also be a harness or circuit issue with the ABS actuator assembly, but, almost every time it's the actuator assembly, itself. Another reason the RPM could drop while in snow is that the traction control system kicks in and the ECM, in response, is cutting the power to the engine, but I doubt that's what's going on. A failing cam position or crank position sensor could do this and they don't always trigger codes. If you have a stock air cleaner, I highly doubt that the issue is to snow getting to the filter, assuming your plastic wheel liner is intact at the driver's front wheel.

thank you once again for a detailed response. i have replaced the crankshaft and both camshaft position sensors about four years ago, so i doubt those are the culprits. the error codes for either of those sensors did not appear on the scan until i replaced the entire ipdm from the factory original revision "B" to the latest revision "C". and their current absence from the scan results would suggest they are fine.

the roads around my neighborhood have been cleared of snow but are now well iced over and quite slick. i drove around in 4x4 for about half an hour and did not experience a single occurrence of the issue. in comparison, it occurred 10-15 times during the same half hour span (and same speed of about 30 mph) i drove during the Wed upper midwest blizzard. strange how a snow-covered road triggers the issue yet somehow icy road does not.

is this the abs ABS actuator/control unit you mentioned: https://www.autoecu.com/2005-nissan-pat ... ctric-unit ? i am having hard time locating it so could you please point me to a reputable site? for instance, i recall you suggesting courtesypart.com year ago, yet i am not able to locate it there.

last question. is it in any way possible to directly test the aforementioned control unit? it appears that the replacement is somewhat complex (bleeding breaks, etc), so i want to be 100% percent sure it is faulty before i spend any money on its replacement.

thank you again!!!

They way you would diagnose it would be to follow the diagnostic steps for those retrieved codes using the factory service manual for your vehicle, which you can access using the "service manuals" link at the top of the page. The link you posted is the ABS actuator. There were several different ones available, so you need to get the correct part number, which you can do by looking up the part by VIN # at a site like CourtesyParts.com or, my preference, NissanPartsDeal.com:

https://www.nissanpartsdeal.com/parts-l ... (2=VQ40DE)

However, they are very expensive ($600+), so you may want to get a used one, which usually run about $150-200. Try a site like Car-part.com.

OMG, I just posted the same problem. Except for me it happens in 4WD or 2WD. There is something funky going on. Is there a way to merge our posts and maybe we can figure out what is going on? This is definitely a winter problem for me. BTW, although we had lots of snow today and pathy was terrible (hesitation several times per minute), I have the same thing happen when it's cold outside and there is no snow. What I don't remember is if there is any precipitation when it happens (I want to say no...).

p.s. no codes for me ever! so, your codes might not be related to this issue.

pls pls pls somebody help both of us