Cliff Harris

I looked through my FSM and could not find a diagram in section 8A that showed anything connected to ground G109. I have a black wire on there, so SOMETHING attaches there. I thought it was the blower motor ground, but the FSM says that goes to G104. Here's the mystery ground:

65Z01

On pp 201-2b of my '88 FSM shows one large connector to g104 on the engine block (assume that's batt or chassis) with three smaller connections.
On pp 14-5 is shown the connections to g104, including:
1-g101(ground strap)
1-s111
2-ECM
1-ESC
1-g100
-wiper washere motor module

WVZR-1

I believe the error is the wiring schematic for ground distribution in the FSM "as published". There was a substantial supplement to the '86 FSM and I don't know that it was covered in it or not. In later years which should have been "VERY" similar, these components which seem the same within reason utilize the G109 ground and reference the same harness splice S116, all of the AC switching sensors, compressor clutch, blower module, blower motor and the washer pump motor.

Do you have the '86 supplement?

I looked at '87 and '88 to rationalize this and there's no way for me to confirm BUT if you remove the ground I would think you would loose function of those components. Is it worth the effort unless you have issues with those components? Likely not but it could certainly be relevant in some diagnostics.

Is there maybe a wire to G104 from the S116 splice as well as the wire to G109 that you mention exists on your car? There is no reference to G109 in any of the text and wiring diagrams in the '86 FSM as published.

OR

Is the image you posted incorrect and on an '86 the G109 doesn't exist. That I believe is NOT the case but then again I don't have an '86 to check. You did mention that you have the wire so you need to I guess draw your own conclusions.

"65Z01" - you should be able to confirm that from the ground distribution in your '88 FSM that seems to be very close by!!

Cliff Harris

Yes. G109 isn't in there either.

My guess is that the FSM is wrong and the ground connection for S116 actually goes to G109. I didn't want to tear apart my wiring harness to find out.

Another one related to this is that the location diagrams in the back of section 8A do NOT show G201, even though it is mentioned in multiple places.

Here's a funny one: I have the Bishko FSM on CD that is searchable, and it found G109 as an example on page 8A-4-0. I'm sure that is NOT a diagram for a Corvette, but only a generic example.

WVZR-1

Yes that's an interesting coincidence that I did notice.

s carter

as odd as may seem when we would have one of the All LCD dash C-4s come in with Flickering/Inoperable dashes that was the first thing we cleaned and checked before pulling and sending the Dash out for repair. in fact if something didn't work we would clean and check it.

WVZR-1

When I mentioned "coincidence" I was referring to the G109 reference in the "introduction" to the electrical section.

I believe you're referencing the G201 in the vicinity of the drivers kick-panel, inner sill trim. Yes that's certainly a "go to" point for many checks. If you were an '89 or earlier owner it might be one of the first areas I'd inspect and maybe confirm.

s carter

that is why it is a as odd statement because I to looked at a very respected colleague and said What? did as he said and things cleared up. I believe it may be a redundant ground for dash Possibly ECM. but then again I am going off of 25 year ago memory's

Cliff Harris

A lot of the interior electronics are grounded at G201. That's why I think it's weird that it's not shown in the location drawings.

A few years ago I scanned all the ground drawings in my FSM:

http://home.earthlink.net/~cliff_har...s/grounds.html