Ground locations

Hi all,

Does any one know what the two earth leads which got to the LH strut tower do? They look to be in parallel, each has one end connected to the engine unit (or to the engine mount which is connected to that, and the other ends both bolt to the strut tower. Are they both basically doing the same thing, but each providing extra capacity?

I presume the one on the steering unit is for the beastly electric steering?

I observe a resistance of 0.3 Ω between engine and strut-tower, which is a bit high if any appreciable current is flowing.

And does this serve for the earth return of the HV supply, or is that wired through separately? I seem to have an intermittently weak connection in this area - unpredictable regen behaviour, recently including a skittish display. I was going down a hill with lots of regen when suddenly the display started flicking back and forth in a way I've not previously seen. It is also slow to wake up from a cold start, and sometimes needs 'prodding' – a brief jab of throttle to get a moment of assist, after which a reluctant regen will usually reawaken. Also, sometimes the over-run regen won't have it, but the braking will; other times only the over-run works. Usually they both work...

But if the current is small it probably doesn't matter..?

Best regards, Tony.

The two ground leads in the engine bay offer redundancy... they're very important, as you may know.

The 300 mOhm you're reading might not be accurate. To test low resistances accurately, you need to push a fairly high current across the device under test, then measure the resulting voltage with a voltage meter USING SEPARATE LEADS. For example, if you push 10 A across the lead and measure 3 V, then your measured resistance is 300 mOhm (3 V / 10 A = 300 mOhm). You must use separate leads for current injection; otherwise you'll be measuring the resistance across the current injection leads, too.

To clarify, set a constant current power supply to output 10 A, then touch one lead to each of the bolts attached to the cable. Now measure the voltage with your volt meter, but make sure you don't touch the current injection probes. This is called 4-wire resistance measurements.

The reason a standard resistance meter isn't going to accurately measure is that they only output 1 mA on the high end. With a 300 mOhm load, the meter is actually only reading 300 uV, which is a very small value... thermal emf and junction potential are all going to add considerable measurement error. Pushing more current overcomes those physical limits.

...

The "HV supply" is the IMA motor, which is a Delta configuration, and thus has no neutral lead. You're thinking it's a Wye, which would have a neutral line.

Based on your symptoms, it sounds like you may in fact have weak ground leads. The reason they're so important is that the various low noise systems - including the IMA computer (MCM & BCM) aren't grounded to the chassis, but rather are connected to the engine's ground via dedicated leads in the loom. When the ground straps start failing, there's no solid ground path from the engine back to the battery and DCDC converter, which are both grounded directly to the chassis. This causes the engine ground to raise about the chassis ground, which cause logic ground reference mismatch, and then all hell breaks loose.

Links to pictures of all grounds and other electrical components in their locations
[/url]https://docs.google.com/spreadsheets/d/1bLUyuFXWywH0PIzTXYtT6UprBNkOtjnWh5PFKjDFylA/pubhtml?gid=883370469&single=true [/url]
^^^^ paste link into browser to view the component location sheet .
or follow links to other electrical component locations and diagnostics, [codes].
for future ref:
ALL GROUNDS LOCATIONS: [.pdf ]
https://drive.google.com/file/d/0B6EDknyr-8unQVNTbWJ2R0JhVnc/view?usp=sharing
G1 - At center rear of engine compartment.

https://docs.google.com/file/d/0B6EDknyr-8unRThIVTdRbnRLSmM/edit
G2 (CVT) - At left side of engine compartment.

https://docs.google.com/file/d/0B6EDknyr-8unV1daWUMyUkxGQlU/edit
G2 (M/T) - At left side of engine compartment.

https://docs.google.com/file/d/0B6EDknyr-8unRThIVTdRbnRLSmM/edit
G3 (CVT) - At left side of engine compartment.

https://docs.google.com/file/d/0B6EDknyr-8unV1daWUMyUkxGQlU/edit
G3 (M/T) - At left side of engine compartment.

https://docs.google.com/file/d/0B6EDknyr-8unTVlzSnJqa0ZmYnM/edit
G4 - At left side of engine compartment.

https://docs.google.com/file/d/0B6EDknyr-8uncnNGdUNBT005a28/edit
G101 - At top rear of engine.

https://docs.google.com/file/d/0B6EDknyr-8uncUFKeTdhQ0VNSUk/edit
G102 - At top rear of engine.

https://docs.google.com/file/d/0B6EDknyr-8uncFg2b0p1WEJiSVk/edit
G201 - Above right front wheelwell.

https://docs.google.com/file/d/0B6EDknyr-8unTmgtV3I0aWlhOEU/edit
G301 - Above left front wheelwell.

https://docs.google.com/file/d/0B6EDknyr-8unSlU0dF9OSnNSN1U/edit
G401 - Behind top of left kick panel.

https://docs.google.com/file/d/0B6EDknyr-8uneWVaMjFrMGZPMlU/edit
G402 - Behind left side of dash.

https://docs.google.com/file/d/0B6EDknyr-8unLXdESzlDRGJIYXM/edit
G403 - Behind center of dash.

https://docs.google.com/file/d/0B6EDknyr-8unRVd6UzMxcWN0WEU/edit
G404 - Behind right side of dash.

https://docs.google.com/file/d/0B6EDknyr-8unY09VcEtxUGpDT1k/edit
G451 - Behind right kick panel.

https://docs.google.com/file/d/0B6EDknyr-8unelhIVG5naFZ3ckE/edit
G501 - Under SRS unit, at front of center console.

https://docs.google.com/file/d/0B6EDknyr-8unSll3WUhGNlRPdzA/edit
G502 - Behind rear seats, at center of floor.

https://docs.google.com/file/d/0B6EDknyr-8unekk3QWFwMkZxSVE/edit
G601 - At center rear of cargo area.

https://docs.google.com/file/d/0B6EDknyr-8und2ZVLXgxbFB4cE0/edit
G651 - At left rear side of floor.

https://docs.google.com/file/d/0B6EDknyr-8unN0JxNDVlVVBXYTg/edit
G701 - At center rear of roof.

I hope that helps. If you have a code you can check here.
>>> [/url]https://docs.google.com/spreadsheets/d/1bLUyuFXWywH0PIzTXYtT6UprBNkOtjnWh5PFKjDFylA/pubhtml[/url]

[used raw urls so newby's will get it]

insightbuyer said:

In the first post there was mention of a G4 and T5 ground strap. Can someone find this on a honda parts website? I can't seem to locate these in the car or online looking at the parts diagram.

Is this one important to check and replace?

Thanks.

Click to expand...

https://www.hondapartsnow.com/genui...t&Year=2000&Submodel=&Filter=(bt=2,391;et=2,3)

thanks for posting the information. Appears it takes 4 ground cables total if you want to replace all of them under the hood. At least that is what i'm ordering from hondapartsnow dot com. I have a few spots of green oxide on the exposed copper, and loose strands in the crimped ring terminals. Might as well replace them all to avoid issues.


Part No.: 32600-S3Y-A00
Cable Assy., Battery Ground
[Insight | 2000 | 3 Door DX (A/C) | KA 5MT]
Remove
$7.78


Part No.: 32601-S3Y-J00
Cable Assy., Transmission Ground
[Insight | 2000 | 3 Door DX (A/C) | KA 5MT]
Remove
$7.78


Part No.: 32610-S3Y-000
Cable Assy., Sub-Ground
Remove
$7.78


Part No.: 53671-S3Y-003
Cable, Grand
[Insight | 2000 | 3 Door DX (A/C) | KA 5MT]
$20.45