I want to use this Grand Am cluster in my 3.4 DOHC Fiero:

The speedometer should work fine with the buffered output from the ECM, no problem. I think all the senders are the same for oil, temp, and fuel as well.
I have two remaining problems: converting the tach to work with the V6, and resetting/changing the value on the odometer to match my old one (the GA uses a digital odometer/trip counter).
I haven't yet retrieved the connector so I haven't been able to power up the instrument cluster to see what the odometer reads, if it even works. The Grand Am cluster actually plugs into the dash through a single connector built into the dashboard, unlike the Fiero which has free male connectors that plug into sockets on its instrument cluster. I'll pull a dash this weekend so I can get the connector out of it (and the external trip counter switch) and get it hooked up for testing.

Does anyone know what component needs to be changed to get the tach to read properly for a DIS V6?
Here is the best schematic I could draw for the night:

I tried to gather as many of the component values as I could.

I imagine this chip has something to do with the odometer. Do digital odometers of this vintage actually use nonvolatile solid state storage? Its from an '88. Otherwise just the controller I guess, and then I must have a battery cell somewhere I can remove so it resets, right?

Here's something cool. The tach comes out with 5 screws and has all of the necessary circuitry and hardware to run itself in this small package.

Just add tach signal, 12v+ and ground. This would make an excellent candidate to swap into a custom dash. Its also incredibly easy to make a new face for it because its just held on by two screws and made of thin multilayer material that can be replicated with supplies from Office Depot or Staples, and a decent ink jet printer. The tach has a mechanically limited sweep (in the driver, not by pins on the face) that would allow it to go to about 10K RPM with the stock scale if you had a face that was marked for it.

BUMP!

Anyone have a wiring diagram for this bad boy?

Give you a bump. How wide is it?

It is 13.75" wide.

I picked up the connector for the cluster today, as well as another instrument cluster that is basically the same except with analog odometer and trip counter. I will use that one if I can't adapt the digital one. Still looking for wiring diagrams, and information on converting the tach..

I have no idea if this is at all correct, but my thoughts would be...

The tach filter. IIRC, when one does a V8 conversion, you must replace the tach filter with a V8 one, not an L4 or V6 filter. No modification to the tach itself necessary, regardless of what engine your Fiero originally had. Fierobsessed put a Sunbird cluster in his car that looks a lot like yours because he needed the tach like you for his Quad 4 DOHC. He modified the cluster so he could put the Sunbird gauges in the Fiero cluster, but I don't recall him modifying the tach itself in anyway. Really, all the tach does is go up or down depending on the input. Only thing different is the scale on the face.

quote Originally posted by Fastback 86: I have no idea if this is at all correct, but my thoughts would be... The tach filter. IIRC, when one does a V8 conversion, you must replace the tach filter with a V8 one, not an L4 or V6 filter. No modification to the tach itself necessary, regardless of what engine your Fiero originally had. Fierobsessed put a Sunbird cluster in his car that looks a lot like yours because he needed the tach like you for his Quad 4 DOHC. He modified the cluster so he could put the Sunbird gauges in the Fiero cluster, but I don't recall him modifying the tach itself in anyway. Really, all the tach does is go up or down depending on the input. Only thing different is the scale on the face.

The tach filter is not involved in signal conversion in any way. It just "cleans" up the signal so the tach electronics don't get erratic pulses.
The tach reading changes depending on the number of pulses it gets from the distributor/ignition module. Because there are more firing events per revolution in an engine with more cylinders, the tach has to be modified for the new number of pulses per revolution.
The Sunbird tach has to be modified to work with a V6. Fieroobsessed wouldn't have had to modify the Sunbird cluster for his Quad 4 because the Sunbird tach is designed to work with an L4. That does give me an idea though.. perhaps the Sunbird tach has a circuit more similar to the Grand Am tach than the Fiero tach is... I'll have to find out what is done to convert that one.

[This message has been edited by Steven Snyder (edited 09-12-2005).]

Since I couldn't find a wiring diagram/connector pinout I traced it all out myself and came up with this for the cluster with the digital display:

Pin # Description Wire Color
1 Gauge Ilumination (12V positive to activate lighting) Gray
2 Ground Black
3 - -
4 ???? Digital display Pink / black stripe
5 "Trip Set" button for display Tan / white stripe
6 - -
7 Tach input Light blue / black stripe
8 ???? Digital display Tan / black stripe
9 ???? Digital display Grey / white stripe
10 - -
11 Low coolant lamp (ground to light) Grey
12 Service engine soon lamp (ground to light) Dark brown / white stripe
13 Oil pressure gauge Tan
14 Coolant temp gauge Green / white stripe
15 Fuel level gauge Pink
16 ???? Digital display Dark green
17 - -
18 ???? Digital display Black / white stripe
19 "Eng/Met" button Light blue
20 Brake indicator lamp (ground to light) Tan / white stripe
21 Ground Black
22 Gauge Ilumination (12V positive to activate lighting) Grey
23 - -
24 Seatbelt Lamp (12V positive to light?) Yellow
25 High Beam indicator (12V positive to light) Light Green
26 Right turn signal (12V positive to light) Dark Blue
27 ???? For digital display (possibly backlighting) Orange
28 ???? Digital display Brown
29 "Trip/odo" button Purple
30 Speedometer signal (buffered, from ECM, 4000ppm) dark green
31 Ground Black
32 Left turn signal (12V positive to light) Light Blue
33 Charge indicator Brown
34 Battery 12V (+) hot in start/run Pink / black stripe
Note: "Eng/Met", "Trip/odo", "Trip Set" buttons are momentary on switches to ground

I still don't know how to wire up the digital display properly, but I'm hoping to have time this week or next to get a closer look at the Grand Am to see where the wires go.

[This message has been edited by Steven Snyder (edited 09-12-2005).]

Mmmmm . . . An 8K tach. Sorry I can't be of any help on the electrical, but I'll sure be watching.

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1988 GT, 5-speed, white, beechwood leather, 3.4 DOHC installation in process.

I put an 86 Sunbird GT cluster in my Fiero. It is alot simmilar to yours, I also have a 1990 GA cluster, but I liked the Sunbird one better. I have a Quad 4 in my Fiero, and I just plugged the wires up and everything works. The sunbird had a 1.8L with a distributor, and the Quad 4 is DIS.

Oh, the Grand am dash of mine, used different pins than the Fiero cluster used, they are narrower, so you would have to add them. My Sunbird uses the same size pins as the stock Fiero cluster, and also only uses 1 16 pin socket, so I had alot of extra wires.
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[IMG]
84 Fiero Sport Coupe #1192 :: 86 Fiero Base Coupe Quad 4 :: 84 Chevette CS 4 Door

[This message has been edited by befarrer (edited 09-12-2005).]

I took a look at the Sunbird tach. It's completely different. Different circuit, different mounting provisions, different connections. The Grand Am cluster doesn't use pins that press into the back of the housing like the Fiero or Sunbird clusters do.
Do you have any pics of your Grand Am cluster? Maybe it was from a V6; they have a different one. I have two Grand Am clusters from a Quad 4 now and neither of them use pins like the Fiero cluster...

I did make a breakthrough in getting the recalibration worked out. Check out this link:
http://www.autosoftsys.com/supra/tachcompare/
The Toyota Supra used the exact same circuit board, IC, air core, etc as this tach. If that pic didn't have a caption I would've thought it was this Grand Am tach on my desk. There are a few differences in component values (mostly resistors, but one capacitor is different) though, so I still haven't narrowed down the component to change..

My cluster is from a 1990 Grand Am SE with the Quad 4 HO and a 5-speed. Looks the same as yours but in KM/h and with an analogue odometer. Also, the Canadian models have an idiot light that tells you to turn your headlights on.

I went with the sunbird because it was from the same year as my Fiero, and the font and everything looks simmilar to a Factory V6 Fiero

A problem you are going to have is getting a faceplate for that cluster, mostly because the idiot lights are eveywhere on that dash.

D'oh! Just got word from Toshiba:
"Hello, Steven!

T2685A is an obsolete part and therefore the data sheet for it is unavailable.

Regards,
The TAEC Tech Support Team! "

quote Originally posted by befarrer: A problem you are going to have is getting a faceplate for that cluster, mostly because the idiot lights are eveywhere on that dash.

Dude.. all the idiot lights are in the cluster.
Everything works without mods except the tach because its set for a 4cyl not my V6. The idiot light wiring and all is the same.

[This message has been edited by Steven Snyder (edited 09-14-2005).]

If all else fails in re-setting the odometer, take it to a speedometer repair shop and they can re-set it for you. I would not expect this to be easy, since ododmeter rollback on used cars can be a big legal issue ....

[This message has been edited by PaulJK (edited 09-14-2005).]

quote Originally posted by Steven Snyder: Dude.. all the idiot lights are in the cluster. Everything works without mods except the tach because its set for a 4cyl not my V6. The idiot light wiring and all is the same.

Oh, no, I mean, they are located everywhere on the cluster. Not all in one location like the stock Fiero cluster or my sunbird cluster. Come to think of it, I remember someone with a Quad 4 Fiero using a Grand Am dash exactly like that, I PM'd him and he said it came with the car wired up but he had instructions that he couldnt find. I remeber his car being a white notchback.

quote Originally posted by befarrer: Oh, no, I mean, they are located everywhere on the cluster. Not all in one location like the stock Fiero cluster or my sunbird cluster. Come to think of it, I remember someone with a Quad 4 Fiero using a Grand Am dash exactly like that, I PM'd him and he said it came with the car wired up but he had instructions that he couldnt find. I remeber his car being a white notchback.

Yeah, the physical locations dont matter though; cause I'm not just dropping the gauges in themselves, just taking the whole cluster box and wiring up the Grand Am connector on the back to the Fiero wiring. I think that's ShaddowGT (sp?) you're thinking of. I recall seeing pics of his, it appeared to have been trimmed to fit in the stock Fiero dash pod so it looked pretty stock, esp since the Grand Am cluster has the 88 Fiero "dot matrix" pattern on its face plate too.
Thing is, he has a Quad 4, so the tach is not a problem for him. Nice to know that someone else got this cluster to work otherwise though. Do you know if he used the one with the digital odometer or the analog?

Not to get overly simplistic, but is there a way you can hook it up temporarily to your car and see if it works without modification? Is your motor back together yet?

Currently building it at the machine shop. Got the bottom end together today. Will install the timing chain and front cover tomorrow, and maayybeee the heads if they are done.
I know it will all work except the tach.
I may just wire it all up tomorrow night or Friday and then when my engine is actually running I'll put a pot across a few resistors I think may be the ones to change, and see what happens when I mess with the values. I have a scan tool now so I can see what the ECM says the actual RPM is.

[This message has been edited by Steven Snyder (edited 09-16-2005).]

Mounting the cluster is going to take more than trimming the Fiero's instrument pod housing. Going to have to do some fiberglass work so this will be on hold for a little while. I need to finish my engine first.

I figured as much. That GA cluster is pretty wide compared to the Fiero's. Good luck with all of it. 2 months till the Coast Run!