PCB questions, bad solder joints

Thread Starter

cjcocn

Joined Jan 1, 2021
11
Hello again.

emailed a business that works on these types of units exclusively and he figures it’s a broken pin inside the PCM.

packaged up my PCM and IDM and sent them to him for testing and repair.

Post office said 8 days to get them there (ha!) and I should have them back within 3 weeks.

I’ll post up his findings once I hear from him.

cheers
 

jpanhalt

Joined Jan 18, 2008
11,087
Don't get your hopes up. My daughter in MN sent me her usual Christmas package on December 14, priority mail I got it yesterday, January 7 (24 days). Christmas presents to grandkids took 14 to 16 days. Be patient. The pony express from Western Missouri to San Francisco only took 10 days. but then, things are much more complicated today.
 

Thread Starter

cjcocn

Joined Jan 1, 2021
11
Hello again!

The PCM was received fairly quickly by the company I sent it to - the mail here is very, very slow, but only for incoming mail. Outgoing mail is still okay.

Here is a partial quote on my PCM’s test results.


“The problem was just what we suspected--several of the connector pins were not solidly soldered into the printed circuit board, and when they wiggled and lost connection, all sorts of things went wrong.
We had to clean all the conformal coating off the connector area, suck the solder out of all 104 pins, and resolder them all, (and we had to do 4-5 of them three times before we got a solid connection).”

The PCM was retested to ensure that all pins now had a good connection and once I received the email from them I paid for the service so they were able to mail my components back to me today.

Now the incoming mail issues may hold this up, but as soon as I get them back I will install them and take the truck out for a test drive and some specific driving maneuvers to help the PCM relearn.

My next update should be a report on the successful repair and more accolades for the help that you folks have given me.

cheers!
 

jivenene

Joined Jan 2, 2021
5
Hey that's great news! Hope it fixes all your issues.

Also, when you re-install, pay extra mind to how the cables are routed and tie them off so as not to put strain on the connectors. You sound pretty knowledgeable so I'm sure you know that already. There are quite a few times I have had to fix wiring that wasn't prepared correctly from the factory in cars and motorcycles!

Jive
 

narkeleptk

Joined Mar 11, 2019
558
I did not read much in this thread but I work on these same units all the time so figured I'd chime in. Can't say I can recall any EEC' units with bad joints on the connector, did it get kicked or maybe you had been wiggling it around too forcibly? If your repair comes back not fixed you may want to check the wire terminals in the main harness for breaks. This would have gave you the same symptoms and then things made worse by over wiggling the connector on the eec unit.

the first pic shows what I perceive as the bad solder joint and it’s positioning under the aluminum frame that the PCB is attached to.
You could just reflow all the pins from from the other side. No need to remove the connector or case.

The second pic shows the grey substance that I think is either an adhesive or more likely a “shock absorber” to reduce impacts to the PCB.
Its a silicone thermal adhesive connecting the pcb to the case frame which acts like a heatsink for the igbt's and vr's. No need to remove it there is only some traces and via's there.

The third pic shows one of the machine screws that has the head soldered. If I remove the PCB to access that area that is circled in the first pic, I would have to heat up those two screw heads and wick away that solder to access the screw head and facilitate its removal..
It wicks away easy then you use a 5/32 socket to unscrew it. But there is no need for you to remove it unless your chasing the circuit checking for traces & via's .
 
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Thread Starter

cjcocn

Joined Jan 1, 2021
11
Good morning!

Received the IDM and repaired PCM yesterday. Mail was slow and even though it was shipped Priority International there was no movement on the tracking info since February 1, 2021.

Put in a service ticket last week and that prompted them to find my package and deliver it.

Installed the components and checked for my 5 VREF. It was there so I buttoned everything up and fired up the truck and drove it out of the garage to warm up.

Took it for a short cruise then took it for a three hour cruise.

Sure is nice to have that truck running again!

Thanks to everyone for their input and support. Your knowledge really helped me figure this out and kept me on the right path so I didn’t do any damage lol.

Ended up buying some interesting tools and equipment, and also learned a bit about materials and supplies that are specific to working with wiring and circuit boards.

I still don’t know anything about circuits, but I certainly found a great place to learn about them and once my garage is cleaned up a bit I will be playing around with some old circuit boards and getting used to working with them.

Thanks again!
 
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