Honda Pilot - Honda Pilot Forums banner

1 - 9 of 9 Posts

·
Registered
Joined
·
866 Posts
Discussion Starter · #1 ·
My '12 had been making a whining noise that changed pitch with RPM, which came and went since Nov last year. I stethascoped it back then to make sure it was culprit (it was) and also measured the charging voltage, ripple voltage and charging current, which were all nominal. Just last week @ aprox 131,000 mi, the whining suddenly increased in volume, and the charging voltage was erratic between 12.2 and 12.8v at idle. With the A/C on, the truck stalled once at a traffic light; assume the charging voltage was really erratic and the PCM became unhappy. I replaced the alternator with a Denso refurb from Rockauto. $145 + core charge. Charging normally and quiet, now.

On a similar note, three weeks ago I got a P0685 code and check engine light. According to Google searches for cause, the main PCM relay often sticks "on". It doesn't cause any drivability issues, although I suppose if the truck were left sitting for a week, it might drain the battery flat. I pulled both primary and secondary PCM relays, nipped the corner of cases off to expose about 1/16" hole, and spritzed the innards with Deoxit, shook out the excess, sealed the hole with hot glue. Cleared codes. Thus far fault-free. The genuine Denso replacement relays are STUPID $$$.
 

·
Registered
Joined
·
3,728 Posts
Nicely done on both accounts!
 

·
Registered
Joined
·
9,383 Posts
My '12 had been making a whining noise that changed pitch with RPM, which came and went since Nov last year. I stethascoped it back then to make sure it was culprit (it was) and also measured the charging voltage, ripple voltage and charging current, which were all nominal. Just last week @ aprox 131,000 mi, the whining suddenly increased in volume, and the charging voltage was erratic between 12.2 and 12.8v at idle. With the A/C on, the truck stalled once at a traffic light; assume the charging voltage was really erratic and the PCM became unhappy. I replaced the alternator with a Denso refurb from Rockauto. $145 + core charge. Charging normally and quiet, now.

On a similar note, three weeks ago I got a P0685 code and check engine light. According to Google searches for cause, the main PCM relay often sticks "on". It doesn't cause any drivability issues, although I suppose if the truck were left sitting for a week, it might drain the battery flat. I pulled both primary and secondary PCM relays, nipped the corner of cases off to expose about 1/16" hole, and spritzed the innards with Deoxit, shook out the excess, sealed the hole with hot glue. Cleared codes. Thus far fault-free. The genuine Denso replacement relays are STUPID $$$.
Now this is useful info. Thanks for posting. ?
 

·
Registered
Joined
·
13 Posts
I pulled both primary and secondary PCM relays, nipped the corner of cases off to expose about 1/16" hole, and spritzed the innards with Deoxit, shook out the excess, sealed the hole with hot glue.
AVC - I also have the P0685 code on my pilot and would like to ask if you would please confirm the image below or otherwise include a picture (or some identification info) so that I can locate the correct relays in my pilot? (& Thanks!)

135791
 

·
Registered
Joined
·
2,254 Posts
While I admire the McGiver solutions that get us home safely or help with diagnosis, replacement of those relays is really a better longer-term option than washing off the slag on the contacts. In my limited experience anyway.
 
  • Like
Reactions: bdozer1965

·
Registered
Joined
·
866 Posts
Discussion Starter · #6 ·
In this case, I preferred the "Russian" fix. Understanding the failure mode (won't leave me "stranded" unless I park the car for a week), and that for 40 years I have used Caig to successfully remedy sticking contact relays, I'm OK with it, rather than $100 in relays. Maybe the same for other DIY's. Maybe not. They have gray matter. Maybe the fix lasts a few months, or a few years, or for the life of truck. Whatev....

As for the relay locations, I'll try to pop the hood this evening and look (it's my wife's daily driver)
 

·
Registered
Joined
·
2,254 Posts
What's so special about those two besides the red cases? Do they have suppressor diodes built in? Trying to decide what makes them $110 for the pair...
 

·
Registered
Joined
·
866 Posts
Discussion Starter · #9 ·
They're ultra-high MTBF.....LOL.....
 
1 - 9 of 9 Posts
Top