North American Turbocoupe Organization



Analog->Digital dash conversion
segfaultxr7 Offline
Posting Freak
#1
I've always liked digital gauges. I've been meaning to get an aftermarket boost gauge, so I thought it would be cool to get the full digital dash out of another T-Bird and install it in my 88TC. That way I'll have the digital dash, and no redundant boost gauges. <a href="http://www.coolcats.net/tech/general/clusters">This site</a> has the wiring info. It looks doable, but I have a few questions/issues..

It has inputs for low washer fluid, door ajar, lamp out, etc. Does anyone have a wiring diagram for the systems sentry so I can move those wires to the dash?

I don't know what the following wires are for the digital dash: "IAR feed", "IAR out". Any ideas what IAR is?

The tach is obviously going to be set up for the V6/V8. There's probably a jumper somewhere to switch it. Is there anything available that can take the 4-cylinder signal and double the # of pulses to make it look like a V8 to the tach? I might just take the bulbs out for it and add an aftermarket tach to go with the boost gauge, I haven't decided yet.

It has a fuel computer. I already added the optional trip/fuel computer and tapped into the fuel flow wire on the LA3, so that won't be an issue.

I have an extra gauge cluster from my '93 Cougar somewhere, it has spaces for Firm Ride and ABS lights, intended for the Super Coupe. Hopefully I can cut them out and transfer them to empty spots on the digital cluster, and install lights for those.

I think I heard somewhere that the digital cluster uses a different fuel level sender. Is this true?

Has anyone else attempted this? If anybody has wiring diagrams or diagnostic/service info for the analog and digital clusters and/or the systems sentry, it would be greatly appreciated. Thanks!
88 TC 5-speed
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Pete D Offline
Administrator
#2
I can send you scans of the lamps out warning module circuit. That's the only ones I have scanned that might help you. Send me an SASE and I'll xerox some of the other circuits for you. I don't know what IAR is.

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NATO Member. it's not a vice, it's an obsession
"The nice thing about each new day is nobody ever used it before" Barnaby Jones
88 TC X 2, 86 SVO, mods list at
http://www.turbotbird.com/showroom/pd_88tc.htm
Pete Dunham


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Jeff K Offline
Administrator
#3
Not only is the fuel sender different, but the oil press and coolant temp sensors are also different (they are 2 wire "floating" sensors, not one wire grounded sensors). I could be wrong, but I dont think the tach has jumpers for different # of cyls. Might be able to get one of those aftermarket converter boxes for adapting tachs to DIS systems to work, but I am not 100% sure exactly how it would be done.

IAR ??? thats a new one on me!!

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Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 20 psi, forced air intercooler, water injection, bypass valve, Ranger roller cam, subframes, etc., etc.. // 86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP nitrous, ignition, gears, suspension, etc., etc.... // 91 Escort: Bone stock winter car // 00 Windstar (wifes vehicle)
Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 24 psi, forced air IC, water injection, BPV, Ranger cam, subframes, etc., etc.
86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP N2O, ignition, gears, suspension, etc., etc.
05 Taurus SEL Duratec daily driver
04 Taurus Duratec (wifes car)
02 Pontiac Grand Prix GT
95 Taurus GL Vulcan winter beater
67 Honda 450 Super Sport - completely customized
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segfaultxr7 Offline
Posting Freak
#4
Thanks, guys! Pete, I got the scans you e-mailed me, I really appreciate that.

I suddenly remembered I had a 92/93 Popular Mechanics CD with complete wiring diagrams. I looked up a '92 Mark VII and found that a good bit of the wiring is very similar. I also noticed that it has those 2-wire sensors you mentioned, Jeff. They all are grounded into a common "signal return" line at the EEC. Is that just a ground? If so, the sensor type doesn't matter assuming it has the same resistances under the same conditions, right? I am going to research that, hopefully they are the same.
88 TC 5-speed
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TurboE Offline
Posting Freak
#5
From what i have been told the computer supplies a ground, for example i know it supplies a ground for the fan temp switch, but i am definately not an expert on this.
-88 TC Black
5spd, Precision SC50 T3/T4, QH/SD Tune, Gillis, AFPR, 255FP, WB O2, K&N, Ported E6, 3" DP, ATR 2.5" Duals, 3:73 Rear, Konis, Eibachs, 18" Voxx Wheels, X Drilled Rotors.
-06 G35 Coupe Diamond Graphite
-97 Pathfinder
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Jeff K Offline
Administrator
#6
I think you might find that the sensor resistances are different for the electronic dash. Not sure, but thats what I seem to remember, so be sure to check out the sensor resistances. In theory, EEC SIG RETURN should be at the same voltage (0 V) as chassis ground, but in practice, this isnt always true due to voltage drops in the SIG RETURN circuit. Usually chassis ground and SIG RETURN are within a few 10s of millivolts of each other, so it might not make much difference if you use chassis ground instead of SIG RETURN.

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Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 20 psi, forced air intercooler, water injection, bypass valve, Ranger roller cam, subframes, etc., etc.. // 86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP nitrous, ignition, gears, suspension, etc., etc.... // 91 Escort: Bone stock winter car // 00 Windstar (wifes vehicle)
Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 24 psi, forced air IC, water injection, BPV, Ranger cam, subframes, etc., etc.
86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP N2O, ignition, gears, suspension, etc., etc.
05 Taurus SEL Duratec daily driver
04 Taurus Duratec (wifes car)
02 Pontiac Grand Prix GT
95 Taurus GL Vulcan winter beater
67 Honda 450 Super Sport - completely customized
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segfaultxr7 Offline
Posting Freak
#7
Cool, thanks very much for the info! I'm going to research those sensors when I have time, I'll keep everyone posted..
88 TC 5-speed
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segfaultxr7 Offline
Posting Freak
#8
I haven't given up on this project! In fact I'm just getting started. [Image: smile.gif]

I found out that the tach has two extra wires, one of which is grounded to recalibrate it for 4 cylinders. So that shouldn't be an issue. There's also a "Check Turbo" light, interestingly enough.

IAR means "Internal Alternator Regulator" or something along those lines, the IAR signal passes thru the cluster and it uses that to determine if the alternator is charging or not. The analog cluster uses the same thing for the ammeter, so that won't be a problem.

The oil pressure sensor might work as-is. The digital cluster uses an on/off pressure switch with a resistor to drop the reading down to the middle of the range. With any luck the existing pressure sender will read correctly, plus it will function as a real (albeit rather low-resolution) pressure gauge.

The fuel level sender will have to be replaced but that's no big deal since I'm going to upgrade the fuel pump soon anyway.

The coolant temp. sensor is causing a slight snag. I picked one up at the parts store that was listed for a T-Bird with the digital dash. I hooked up the cluster to a battery, and attached the temp sensor. It immediately went to max. hot and then showed an error display (2 bars at the top and bottom). It did the same if I shorted the wires together. I measured the resistance, it was 220 ohms at room temperature, which sounds about right. I'm thinking there might need to be an inline resistor. If anyone has EVTM scans for the electronic gauge cluster from an 87-88 T-Bird, it would be very helpful!

BTW, the oil pressure and coolant temp sensors for the gauges are both one-wire units. The coolant sensor is 2-wire if the car is equipped with the auto climate control, though.
88 TC 5-speed
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