P0526-17 (28) Fan speed sensor circuit - General electrical failure - circuit voltage above threshold

[Longtrail]

Hi Folks,

I've been fighting this one for a while now but this weekend tried getting to the bottom of the issue without success; here's the gap tool screen:

Here's what I've tried so far:
- Installed a new viscous fan (Mahle OEM) - no change
- Checked, reseated, cleaned and applied dielectric grease to the connector (driver side near the radiator that connects the viscous fan to the wiring harness) - no change
- Traced the wiring harness across the front of the engine (just above the radiator) to look for any obvious signs of damage - didn't see anything obvious
- Noted two grounding posts just below the passenger side headlight so cleaned and reseated all electric connections there - no change

Next steps:
- Look at the wiring diagram to try and understand the different wires and what I might expect to measure on them (ground, voltage, etc.)
- Determine if there's a relay in the mix here (I've read there is), replace it

Does anyone else have other ideas or experience with this issue? So far I'm working based on my internet search but haven't had success with this yet; the fault comes back immediately after clearing.

Thanks.

 

[Rover Range]

I tried looking up that DTC in the LR manual. Doesn't come up.

Make sure that the fan is spinning "freely." If the motor mounts are sagging, the fan can drag on the fan shroud brushes.

 

[Longtrail]

Thank you. It is spinning freely, I did see others mention motor mounts but every time I've looked at the fan it's turning at the same speed as the pulley on which it mounts so I discounted this (I will off-course double check).

It's weird that it doesn't show up in the LR manual, I swear sometimes this thing has a mind of its own! I have a different OBD scanner I could try that and see what it reports? Also I've had it manifest with this (same code but the number in the parenthesis changes (68) rather than (28)):

One thing I did notice, having changed the viscous fan I noticed on first start that the engine sounded much louder from noticeable fan noise, subsequent starts have been business as normal. I noticed this as a friend has a 4Runner and I always think it sounds really noisy on cold start!

 

[itsaguything]

deleted.

 

[Longtrail]

Update (both good and bad! but mostly good). I used the Autel MaxiAP AP200 and got the same code (P0526 but without the additional numbers); so I used it to clear the code, scanning again the code is gone and didn't come back, I then checked it with the GAP tool and see the same! Weird!

I did check the fan for rotational freedom and it seems to be fine; I also ran my hand around the periphery of the fan and couldn't detect any tight tolerances so I think my engine mounts are OK. I also ran the engine and fan is turning nicely.

I don't tend to post until I know an issue is really an issue, I've been tracking this one for a few months so it's really strange that it should go away now! I will check again later today and report back if it's bad!

 

[Rover Range]

Generic scanners can send you on a wild goose chase.

Pesky little elves, that come fix your car in the middle of the night.....

 

[Longtrail]

I love Elves!

The fact that the Autel cleared the fault and the GAP scanner couldn't find the fault was pretty cool (@Rover Range - do you consider the GAP tool as a generic tool? I realize you get the real tools but us DIYers have to make do with what we can find)! I do have questions about the Gap tool settings but that needs some research before I post.

 

[Rover Range]

Any tool other than OEM is considered generic. Although, the OEM LR tool is suspect at times.
I have a small MAC Tool scanner. It does an OK job.
A Snap On scanner is very spendy. But, probably one of the best.