Hoping some electrical geniuses (or any fine FTE'r) will chime in. Today I decided to R&R some ground points due to some erratic behavior the truck has been exhibiting. Here are my initial results.

My gauge pod has 2 temp gauges (water and tranny), and the water gauge is fed by two separate senders controlled by a 6 position pot. Over the last couple years, the temp gauges have read erratically and lower in general than when first installed years back. I also suspect my sporadic no start condition may also be linked to a voltage anomoly.

Removed the ground below the windshield on the driver side, and the ground on the inside of the driver fender right by the AIS. Both of the ground points had intact paint from the factory, and the factory wire lug appeared to have tabs flared out to "bite" into the body. Well 10 years and ~250k mi must have relaxed the tabs . So I scraped the paint from around where the lug rides, filed the lugs to a shinny "copper", treated with my hi-speed sample of that fluid film, and reassembled everything.

Can't report on the truck starting (so far, it has started 1st time, on every attempt), but my temp gauges are back to 100%. Sooooo, now I want to know if I can "check" the other ground points, or will I just have to R&R them all. If nothing else, those two ground points affected some stuff... to include the PCM and IDM (they both culminate at those ground points)

Any tips?

 

Well I'm no electrical genius but I will chime in until you wait for one. To check for a good ground simply test resistance between a good ground and the one you are testing. It should be very low. Test a good ground to battery ground for a reference. Hard to believe they would use clips for a ground.

 

Another Tim the Toolman here buddy but here's a bump for the experts.

 

Pinch hitt'n A So, if I set my DVM to auto ohms, one lead on the ground wire/lug, other lead on battery NEG, I should have mostly no resistance. OR should I have the first lead on the body panel close to the ground point? Then if it seems good, how about the flow of current, will that impact the connection. I hate electrical stuff, it causes cranial flatulence

And it really isn't clips, it's like the inside of the lug is not a circle, looks like a cog, and the tabs ostensibly were to be tweaked so when you tightened the lug against the metal, it would dig in (kinda like a star washer)

 

Ok ok.. I fixed the post, Ya'll know so MUCH stuff, I put you all in the genius category. I'm just getting older and lazier (is that a word.) so I was hoping for a quick and dirty test. Probably wouldn't hurt to just go ahead and R&R all the ground points anyway.

Oh, and Tim IS the man! A true inspiration to me.

 

Yes he is, an inspiration to all Shucks, if it wasn't for him, I wouldn't do half the stuff around here. Wifes happy, and laughing too..

 

It does not matter on the leads. Just use two good ground points for a reference and go from there.

 

Kewl, Lord willin, and the river don't rise, I'll be doin that tomorrow. Got a typical weekend on deck here in MO... RAIN Sat and Sun!

 

You really need a milliohm meter to measure grounds. They're so low in resistance, that a "normal" DVM won't really show you too much, unless it's grossly out of whack. However, you can address all the ground points and clean them up and put some good anti-corrosive on there (Penetrox, Noalox, etc.). I have to do the same thing.

 

I would set the DVM to no higher than a 10 ohm scale. You are checking for continuity and there should be minimal resistance. Put one lead on the negative terminal (which is where the ground portion of the circuit should end) and one on the blade tab of the ground you are checking. This will be as close to possible to the portion you are testing and provide the lowest resistance path so you won't have to disconnect anything upstream to verify that you aren't getting any parallel paths.

The whole idea was to save on cost by grounding everything to the bare metal of the vehicle and then run a wire from the vehicle to the negative terminal. This cuts production costs, complexity and weight. To put it in perspective, Delta removed one olive (only one) from it's salads that it served in 2009 and saved $40,000. Imagine what the auto manufacturers saved by cutting that much wiring out of their vehicles...

If you have more than a few ohms then you might not have a good ground connection (my personal threshold).

It's mostly my personal opinion, but hopefully some of it helped.

 

Measuring resistance is the obsolete way of doing it.

Measuring the voltage drop is a much better way to check it.

 

Measure voltage drop but under a load.
Small tester will show good connection, while applying 200 amp load will make it open.
I had my dose of electrical nightmares on motorhomes, where perfectly clean and shiny bolt +nut would make open electrical connection. Turns out the small amount of patina on internal surface would block heavy amperage.
For testing such nightmares, where you can not check the connections under normal load -make a tester with 20 or even 40 watt light bulb.

 

Exactly Noalox and Penetrox will assure that they never corrode again, this works very well on battery connections too

 

Thanks for all the ideas, I'll be doing most, save the load tests unless I still have problems after the R&R.

So here's a quick update to the results of just cleaning the afore mentioned ground points:

I'm a full blown audiophile, lately I've felt my passive crossovers on my Quarts was beginning to fail, sound was slightly distorted under volume, and the frequency's were seemingly compressed. NOT any more! Bright, clear, FULL sound. And... the BASS is back. So seems the head unit wasn't happy with the ground, as all the amps are grounded back to the batteries. Another biggie is the idle. I have an APCM (AIC) and the rpms are constantly fluctuating 8-12 rpms. Also not any more. Waiting for PT this morning, ROCK solid on the digital display.. 680! Maybe a 1/2 dozen times it dropped to 679, but that's it. ONE rpm! WOW! From the service manual I know that the CPS is grounded to one of those points, and obviously was impacted by the added resistance. No question now, I'm doing them all. Also, truck still has started 1st time on every attempt so far.

 

Ouch!

I've been called old before, but never obsolete!

Good advice on measuring under load. Especially with a large audio system that draws lots of juice, you might not see any degradation until you start to get higher in the loading.

If I'm troubleshooting a system I will usually use voltage, but when I get down to individual connections I switch to resistance. I'm old school.