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Undertake72 05-07-2021 07:25 PM

1998 sc2 tach issues still
Ok so here hopefully one last time .. I have the autometer model 2300 tach ...then was told I need the tach adapter to make it read properly .. Bought that .. But for the life of me i CANT get it to work at all ...any help would be appreciated very much .. Tach adapter model number 9117

fetchitfido 05-08-2021 12:15 AM

Re: 1998 sc2 tach issues still
[URL=""]Tach Adapter[/URL]
Red -> +12v
Black -> Ground
Red/Green -> Tach signal from PCM (white wire)
Gray -> Gauge

[URL=""]M2300 Tach[/URL]
4cyl = both DIP's down
White -> Grey wire on radio harness (or +12v if you want the backlight on all the time)
Red -> +12v
Black -> Ground
Green -> Gray wire from adapter OR White wire from PCM if not using adapter

All +12v references are key-switched sources, not directly from the battery otherwise it'll drain the battery.

billr 05-08-2021 12:33 AM

Re: 1998 sc2 tach issues still
Maybe I'm reading the Autometer info wrong, but I don't think the above is correct. I think the 9117 goes in series with one of the ignition wires, after it the wire is cut.

What does Autometer say about all this? Do they understand that you are trying to connect to a Saturn wasted-spark system? If they cannot figure out why it won't work, I would abandon Autometer and start over. Trying to "finish the engineering" for a flaky vendor is not often a practical effort.

However, I suppose I should ask: what does it do now, no tach action at all, or still wrong reading? How, exactly, do you have the wires to the 9117 connected to the car?

Undertake72 05-08-2021 02:03 AM

Re: 1998 sc2 tach issues still
Autometer wasnt a great source of help ..they told me to hookup the red wire onto the brown with white tracer off ignition module with the tach adapter then put the red / green wire from adapter to the pcm side of brown/ white wire ...then it should work ...not working at all ...that wire with just the tach reads only 1 cyl lol

billr 05-08-2021 12:31 PM

Re: 1998 sc2 tach issues still
So, it is reading, but at 1/4 the proper rpm?

I'll check out the wiring connections you described and post again later.

I just re-read you last post, I think it is incomplete. You describe how you connected the RED wire and the RED/GRN wire from the 9117 adapter, but I think there are more than two wires from the adapter (4 of them?). How are the other adapter wires connected, and can I assume the adapter is connected to the ach as shown in the (again, [I]poor[/I]) published Autometer info? I will post a link to the info I am referring to in my later post.

Oops,,, no need to post the Autometer info, that was already done in reply #2 by somebody else! Time to study some more now...

Undertake72 05-08-2021 09:39 PM

Re: 1998 sc2 tach issues still
Ok so on my tach adapter "per autometer" I connected the red/ green wire to the ignition module side .. Then the red wire to the pcm side of the brown/ white wire then I got no signal at all at tach ... Brown/white wire is cyl 4 signal output .. With adapter tach didnt work ... Without adapter I got 1/4 signal ... The white wire at the module I got half the signal on tach .. Havent tried the adapter on that wire yet ... But I'm not optimistic on that wire either ... Grrrrrrrr

billr 05-08-2021 11:55 PM

Re: 1998 sc2 tach issues still
[I][B]"The Auto Meter Tach Adapter wires [COLOR="Red"]in line[/COLOR] on the positive 12 volt supply wire. It senses [COLOR="red"]current[/COLOR] on the coil positive wire and converts it to a 12 volt signal output." [/B][/I]

I think you need to put the RED and RED/GRN wires from the adapter in series with the PNK wire to the ICM (pin A).

Cut the PNK wire and connect the RED wire to the ICM side of the PNK wire and connect the RED/GRN wire to the harness (PCM) side of the PNK.

My understanding is the Saturn ICMs have the coil drivers in the ICM, so the individual coil primary currents are not accessible through any of the wiring. The only way to sense coil current is via the 12V supply to all the coils (the PNK wire). I'm not sure, but I think you will find the tach will now read 2X actual speed, so you will need to jumper the tach for "8-cyl"

Undertake72 05-09-2021 09:13 AM

Re: 1998 sc2 tach issues still
I will give the pink wire a try this afternoon ... I will le you know how it goes !!

billr 05-09-2021 11:24 AM

Re: 1998 sc2 tach issues still
I got that backwards last night, the adapter RED goes to the harness, the RED/GRN goes to the ICM. And, the PNK in the harness is coming from the "EIS" fuse, not the PCM; but that is an irrelevant error. It was late for me last night; that is my excuse and I am stickin' to it!

I will PM the OP to increase chances of this correction being seen.

Undertake72 05-10-2021 08:05 PM

Re: 1998 sc2 tach issues still
I got your pm ... So your saying the red/ grn goes to igm side of pink wire and red goes to pcm side of pink wire ?just to clarify ? Because im about to call summit and exchange this adapter incase I messed it up hooking it up wrong !!!!

billr 05-10-2021 10:16 PM

Re: 1998 sc2 tach issues still
Yes, you understood my advice on the PNK wire correctly. Have you tried it yet??? I am eager to see if that works. I'm thinking now that you can leave the tach jumpered for 4-cyl

Undertake72 05-14-2021 07:41 PM

Re: 1998 sc2 tach issues still
Ok hooked it up with your update and works perfectly now !!!! Ty very much on the info !!! And btw it has to be in 4cyl mode to work properly !!!

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