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greatwhite
06-09-2012, 08:44
Well, I got a bit of a fright the the last few days.

Dropped big bucks on the AC and it went flat in days, then my cruise stopped working. I was beginning to think this thing was moving into another "nickle and die you to death" phase (as if $10,000 on and optimizer wasn't enough!)

Pulling codes revealed a history and pending p1621, fuel solenoid response short.

That and the cruise dropping out made me think pmd.

Crap, I just bought that from Bill a bit over a year ago!

It can't be toast already, can it?

I swap in my "just in case" spare I keep in the glove box.

It's an older used black stanadyne one I picked up for 40 bucks and have mounted on a computer heat sink. It aint pretty and I wouldn't count on it as my only one but that little insurance policy in the glove box has gotten me out of some pretty sticky situations. It's more vital to have than the spare tire on a 6.5 IMHO.

Sure enough, cruise works and codes are gone.

And we leave on a 3000km round trip vacation this Friday!

Grrrrrrrrrr.......

Well, let's see what we can find. Maybe it's something simple.

I pulled the pmd/cooler off the truck and gave it a good looking over. Specifically the connectors.

The connector and pins in the pmd looked good.

Crap, I was hoping to see something obvious like a bent pin, filth/grime/corruption or something similar.

Mood is getting low now, figuring it would be chasing down grounds and connectors before condemning the PMD completely.

On a whim, I pulled the calibration resistor. I've got it apart, why not?

On the back side of the resistor was a big fuzz of green corrosion bridging the two terminals.

My heart jumps up into my throat, please let it be that simple.

I cleaned it up with some careful/gentle work with a dental pick and contact cleaner.

Then I put it all back together and took it for a test run.

Cruise works a treat, no DTC's.

JOY!

Dunno why it only corroded on the underside, must have gotten some moisture in it somehow and sat between the housing and the resistor. Seals on the connectors look fine. I'm thinking I might pack it with some grease or dielectric to help seal it all up but haven't decided if that's a good idea or not yet.

But, it's cleaned up and running fine now. Easy fix.

I'm happy, momma's happy, the dogs are happy, my wallet is happy, the truck is happy, everybody's happy!

Phew, crisis averted.......
a5150nut
06-09-2012, 09:16
One of the first thgs I did way back when I first got my truck in 97 was join here. The next was to disconect ALL electrical connections exposed to weather, clean them with contact cleaner, & pack with white grease.

I think I have avoided many gremlins because of that.

Have a safe trip and enjoy the truck.
coxfmly
06-09-2012, 11:25
So it sounds like it would be a good thing to pack the electrical connections with dielectric grease....any down sides or preferred type of grease??
jhornsby3
06-09-2012, 12:02
When ever I disconnect a plug I clean it real good and put the grease on it when it goes back together. Living in the wet I just got into that habbit. For type I like the Super Lube in the grey tube as it is also high temp. I used to use it for lube on high power rocket motors to ease in clean up.

John
racedaymechanic
06-09-2012, 14:17
So it sounds like it would be a good thing to pack the electrical connections with dielectric grease....any down sides or preferred type of grease??
Dielectric is the only kind of grease you should use as its non conductive
coxfmly
06-09-2012, 17:41
I have dielectric grease, does it matter? is their such thing as "bad" grease?
racer55
06-11-2012, 07:19
I would only grease the seal rubbers,not the pins- most grease is an insulator,you don't want to get it in the electrical connections.
DmaxMaverick
06-11-2012, 07:44
Dielectric grease is formulated to be used IN electrical connector contacts. It will not interfere with continuity. It will insulate the contacts from oxidation, electrolysis/galvanic corrosion, and waterborne corrosives (salt). Highly recommended for any/all electrical connectors. On a gasser, it works great in spark plug terminals/boots.
Kennedy
06-11-2012, 07:48
CRC makes this in a spray can. I use this a lot as I can spray on a thin film without excess ooze.
greatwhite
06-12-2012, 11:31
3 days later and still runnin' fine.

The PCM is settling down into it's match with the drivetrain and things are smoothing out again.

My confidence is restored int he old beast.

Just in time too, we head off on a 3500km round trip on Friday.....

:cool:
racer55
06-12-2012, 12:33
Dielectric grease is formulated to be used IN electrical connector contacts. It will not interfere with continuity. It will insulate the contacts from oxidation, electrolysis/galvanic corrosion, and waterborne corrosives (salt). Highly recommended for any/all electrical connectors. On a gasser, it works great in spark plug terminals/boots.
As I said most grease dielectric included is an insulator and non conductive,I prefer to use it to seal a connection vs contaminate it.
Have a read of this thread:
http://continuouswave.com/ubb/Forum6/HTML/001202.html
leolkfrm
06-24-2012, 18:11
do you find the heat sink gets hot to the touch?

did the same thing on my neighbors truck...relocated it by the fuse block, but it seems to get very hot

where did you locate yours?

thanks
racer55
06-24-2012, 19:16
Positioning the FSD/PMD/heatsink combo outside the underhood area is best.
behind the grill on a rad support or under/behind the frt bumper are common locations.

If the heatsink gets hot it may be undersized.
greatwhite
06-25-2012, 02:54
do you find the heat sink gets hot to the touch?

did the same thing on my neighbors truck...relocated it by the fuse block, but it seems to get very hot

where did you locate yours?

thanks

I've got a bill Heath (heath diesel) kit.

If you google it you can find some pics.

It does not get hot. Barely even warm.

Ymmv.

;)
leolkfrm
06-26-2012, 11:57
thanks...mounted it over by the fuse box but it still is hot to the touch..the heat sink in the pics look about 30% bigger than what we used
greatwhite
06-26-2012, 19:13
thanks...mounted it over by the fuse box but it still is hot to the touch..the heat sink in the pics look about 30% bigger than what we used


PMD relocation Rule of thumb:

Biggest heat sink you can fit and mounted outside the engine bay.....
DmaxMaverick
06-26-2012, 19:26
PMD relocation Rule of thumb:

Bigest heat sink you can fit and mounted outside the engine bay.....

Ditto. You have two (somewhat successful) options. Move it outside the engine compartment with a large heat sink, or leave it on the pump. Mounting it inside the engine compartment (except for emergency), heat sink or not, is out of the frying pan and into the fire.