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Author Topic: Grounding straps  (Read 309 times)

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Offline BillT

Grounding straps
« on: March 08, 2020, 10:39:19 AM »
I will soon be rewiring my '52 CJ3A jeep. Plenty of diagrams for the power wiring but haven't found anything for the engine/chassis grounds and the po has added grounding wires and straps. Could someone point me toward some info for the original locations/specs. of the grounds? Thanks
« Last Edit: March 08, 2020, 10:41:33 AM by BillT »
'52 CJ3A, early M38A1, '70 Commando
25' travel trailer, Lance 855S truck camper
Love to camp

Offline Rus Curtis

Re: Grounding straps
« Reply #1 on: March 08, 2020, 11:24:04 AM »
Bill,
Early on, the mechanics helping me with my electrical problems added cables at random spots to complete the ground circuit.  It looked ugly but completed the circuit. 

I later learned that while that can be done (there just needs to be a path past the engine mounts to help the electricity flow), there's only one ground strap that is called for on the jeep engine.  This ground strap is in the same spot for both F and L engines - under the generator attached to the base of the right engine mount.

On the CJ3A Info Page there's an image of the ground strap (center image):
http://www.cj3a.info/tech/battcable.html

And a scanned image (attached below) from the Service Manual (SM).  All other ground connections are through the metal body and the metal chassis (to my understanding, this is why all electrical parts have only one wire; contact with the body/frame completes the circuit). 

For the Fuel gauge, there is one clip holding the fuel line to the tub hat channel that does not have a loom sleeve on it (the tank has anti squeak strips and the fuel line has loom sleeves to help manage vibration as it winds its way up to the fuel pump.

Also from the CJ3A Info Page:  http://www.cj3a.info/tech/line.html

« Last Edit: March 08, 2020, 11:31:51 AM by Rus Curtis »
'54 CJ-3B "Green Gruntt"
Bantam T3-C

Offline SteveKfl

Re: Grounding straps
« Reply #2 on: March 08, 2020, 12:01:56 PM »
The important thing to remember with grounds, is making good clean 'metal to metal contact', not 'on painted surfaces'.  Because I added an electric OD trans, I added another 'ground to frame' on the transmission because the governor uses the housing for grounding the OD circuit, and I wanted to make sure it had a good strong ground.  Weak or poor grounds can make "trouble shooting electricals", a real challenge to isolate, IMO.  I suggest using a continuity setting on an ohm meter to verify contact to metal.  After restoring, it is always a hard thing to do to bare the metal again for contact, but needs to be done.
My Concept Roadster
62 DJ3A Dispatcher Half Top

Offline BillT

Re: Grounding straps
« Reply #3 on: March 08, 2020, 02:07:37 PM »
Rus and Steve thanks for the comments and links. I think the same old mechanics who grounded those jeeps did mine also. lol The grill, distributor, air filter (yep), starter, generator, motor support, voltage regulator, and battery are all grounded to the frame. whew

'52 CJ3A, early M38A1, '70 Commando
25' travel trailer, Lance 855S truck camper
Love to camp

Offline ojgrsoi

Re: Grounding straps
« Reply #4 on: April 28, 2020, 10:52:21 AM »
I wonder if the air filter ground was there as a convenient bolt to ground the body to the chassis.  I had to ground my body and grille to the frame because I had flickering electrical components.  The additional ground cleaned that up.  I tried to conceal those auxiliary grounds in the home made wiring harness so it is not just some goofy wire hanging out there.  It really helped.

I also need to replace body mounts.  Once that is done I am thinking that the body will be grounded better.  By better I mean that with no rubber the body sits there with loose bolts "shifting" around and not making a good tight contact.

Bottom line is if things are working well with your auxiliary ground wires they might be incorporated in your new wiring so you don't have to chase ghost problems.
Mark
51 M38
73 IH Cub 154 Lo Boy

70 USA DJ5 LHD - SOLD, 78 USN DJ5F LHD-SOLD, 67 CJ6-SOLD, 65 CJ5A-SOLD :(, 51 M100-SOLD, 71 CJ5-SOLD, 79 DJ5G-SOLD

Offline BillT

Re: Grounding straps
« Reply #5 on: April 28, 2020, 09:54:39 PM »
Thatís a good point Mark. I have the new wiring harness and will be starting the install in a couple of weeks. And as long as we are talking about grounds, somewhere I saw a grounding strap that was to ground the hood to the body. Whatís up with that?
'52 CJ3A, early M38A1, '70 Commando
25' travel trailer, Lance 855S truck camper
Love to camp