Pennock's Fiero Forum Technical Discussion & Questions - Archive
I Found a home for the 8-pin under-dash mystery plug! Prototype Rally Computer! (Page 1)
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I Found a home for the 8-pin under-dash mystery plug! Prototype Rally Computer!
EDIT: Has ANYONE EVER seen a Fiero with the Rally computer installed? Is there anyone I can contact to find out, maybe GM engineers?
It turns out that the prototype mystery plug under the passenger side dash, taped to the convenience center wiring is indeed for a prototype rally computer. It was planned to display Instant MPG, Average MPG and Miles to destination. Unfortunately, the prototype never made it to production, so the plug was left in the harness. There is even a page in the 86 service manual about the rally computer. All the wire colors match up.
I can't see why not, you probably could get one from another car that has a similar computer and rewire it. We all know Gm has used the same wiring colors for alot of things. Now knowing this plug has alot of wiring going to one spot would make it easier to install someting...-Jason
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07:44 AM
mattman134 Member
Posts: 643 From: Buford, Ohio Registered: Dec 2009
I checked with a multimeter and all the wires go where they are supposed to. The rally computer (if it would have made it into production) would have mounted in the dash where the dash pocket is now.
I can't see why not, you probably could get one from another car that has a similar computer and rewire it. We all know Gm has used the same wiring colors for alot of things. Now knowing this plug has alot of wiring going to one spot would make it easier to install someting...-Jason
I did a quick check on ebay and a few other places for "rally computer" or "trip computer" and couldn't find anything from that era. Maybe I'm searching for the wrong thing.
I did a quick check on ebay and a few other places for "rally computer" or "trip computer" and couldn't find anything from that era. Maybe I'm searching for the wrong thing.
Only thing I could find from that era was off an 80's Jaguar, with a big sticker on the back that said LUCAS.
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02:25 PM
mattman134 Member
Posts: 643 From: Buford, Ohio Registered: Dec 2009
The caddys, buicks, and even some Oldsmobiles during the mid to late 80s had those trip computers available. I'd love to know where this connector you're speaking of is located? Are you saying it's behind the dash?
We have a spare slot on our Fiero in the gauge cluster... could probably put something there, who knows?
The C4 vettes of the 84-89 era had a DIC (driver information center).
There are quite a few on ebay fior $50... just do a search for DIC
Edit: that doesn't sound quite right and I am sure some will have fun with it.
IIRC, that pic is of just the switches and idiot light pod. They control the cluster which has that digital stuff built in to it. I think a Grand Prix (early) would do the trick, it's a stand alone pod. You might be able to make that work...I'll see if I can find a pic of that. -Jason
It doesn't look like anything on ebay has an 8-pin connector like the one mattman134 found. I'm sure it would be possible to make one of the GM ones work with our cars but they are too expensive for me to experiment with.
*Edit to say that I couldn't find the connector on my 86GT. It might be hidden up above the heater box. I'll look tomorrow when I have more light.
[This message has been edited by nutherproject68 (edited 09-28-2010).]
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07:31 PM
PhilipFiero Member
Posts: 94 From: The Netherlands Registered: Jan 2010
IIRC, the pic your showing, that is just the switches and idiot light pod. They control the cluster which has that digital stuff built in to it. I thing a grand prix (early) would do the trick, it's a stand alone pod. Might be able to make that work...i'll see if I can find a pic of that. -Jason
Can't be sure, I'd have to take the whole console apart to get it out - but it looks like the '92 GTP DIC has the same size connector, about 4 pins wide. I checked my service manual but unfortunately it doesn't describe the connector or its pinouts (different volume).
Couldn't really get my camera back there. The back of the housing is open, but it's shrouded and very difficult to see into it while contorted around on the floor with a flashlight. I'll take another look at it tomorrow in the daylight.
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02:41 AM
Fierofreak00 Member
Posts: 4221 From: Martville, NY USA Registered: Jun 2001
8 wires... what sort of wires are we talking about here? I imagine we are doing serial data, as well as power and ground, but that leaves another 5 wires?
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07:57 AM
mattman134 Member
Posts: 643 From: Buford, Ohio Registered: Dec 2009
Here is what was near production. As usual, PMD spent all the money to develop this Rally Computer and at the minute the supplier was ready to ship the finished product to the plant, they cancelled the project. My sources tell me that there were pilot units at the Fiero Plant ready to install waiting for corporate to finalize the financial outlook of the option. Once again, the bean counters got involved and the option was never offered. Another issue I see is that engineering was still finalizing technical data as of February of 1985. In PMD timeline, this would have not been ready until MY1987.
It appears that the option code would have been UV4. Does the 86 Fiero described in this post have the RPO UV4 on the SPI tag on the left fender well under the front decklid?
I do not recall seeing this computer in another GM car. Athough, I am sure the development cost might have went to another GM car.
Fred
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12:45 PM
RAREW66 Member
Posts: 1119 From: Davenport, IA USA Registered: Jun 2001
Here is the rest of the PDM info I have. The dates on the sheets are even later, so I am in doubt as if the RPO UV4 would have been offered as an option in MY1986. As I stated, there is rumor that pilot units were at the plant. Another senario that has come up before is that different suppliers would have provided the different component parts. There is the possibility that the harness was there at the plant and got installed as a fitment test by that supplier.
mattman134, you have a somewhat unique piece there. In addition to searching for the RPO code, does the car have the compass sensor and harness running up the passenger side A Pillar with the compass sensor in the area of the inside rearview mirror?
This subject is a small glimpse of what the future of the Fiero had in store. There are several other items that were in design when the Fiero was cancelled.
Hey guys. I thought I'd let you know what I've been up to for the past few hours. I found this one ebay last night: http://cgi.ebay.com/ebaymot...432924344&viewitem=. It's out of a 94 or 95 Grand Prix GTP. I got the wiring diagrams off of Mitchell while I was at school today. Here is the diagram for the DIC.
Well, I bought the item and I am going do my best to adapt this DIC to my car. Most of the inputs and outputs are pretty straight forward. The pigtail is included so I won't have any problem making a harness. I can get the outside air temp sensor and connector from RockAuto. I don't think I'll need the wire from pin B5. It looks like that just controls the measurement type for the HUD.
I had found the schematics of the rally gauges in the preliminary 86 service manual, but the section is gone in my final 86 service manual, so the option must have been cancelled somewhere between editions.
Maybe I can add what I know to the knowledge pool:
The major difference between the 85-86 V6 ECM and the 87/88 V6 ECM is the addition of mileage code output. At the same time (to save memory?) the code for the knock sensor has been removed. Other than that, the ECMs are identical (with some knock sensor related components being missing on the newer ECMs).
Now, the mileage information is output on the ALDL line, and includes everything needed to display current and average mileage. When the ECM switches to diagnostic mode, the ALDL line outputs diagnostic information, but in normal mode ("road mode"), it outputs rally gauge MPG information.
But this information is not accurate enough to properly calculate current speed, distance, average speed, etc. That's why the VSS speedo pulses are required additionally.
The lights input is probably just for dimming the display, and the fuel sender input for calculating remaining fuel range based on current MPG.
I don't understand the mounting location though - a nice toy for the passenger, but too far away for the driver. I would have expected it to be mounted on top of/next to/instead of the rally gauges on the center console. Who pays for a probably quite expensive option and need a walking stick to reach the controls?
Anyway, it's funny, except for the fuel gauge info (which is usually far off anyway on all of my Fieros), this is pretty much what I have put on my DashScan as inputs - it also displays all of that information except for the fuel range, so you could plug DashScan into that connector...
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06:07 PM
Fierofreak00 Member
Posts: 4221 From: Martville, NY USA Registered: Jun 2001
I went to the junkyard today on lunch and got one of the Grand Prix STE units ( I seen it a few weeks ago, but had no tools to take it out) as luck would have it, it was still there. I fired it up to make sure it works, which it appears to with no issues. Although, the display screen is bit dirty. It came out of a 93 with a 3.1.
Connector is a 16 pin connector and all cavities are filled.
Pin colors are I labeled the ones I know.. A-1 Orange = B+ A-2 Pink/Blk = Switched B+ A-3 Brown A-4 Brown/White A-5 Brown/White A-6 Drk Green A-7 Orange = Data bus A-8 Black = Ground
B-1 Lt grn/blk B-2 Black B-3 Gray = Lighting B-4 Lt green B-5 Lt/blue B-6 Purple B-7 Pnk/White B-8 Black = Ground
[This message has been edited by Fierofreak00 (edited 09-29-2010).]
Do you want me to try and get a diagram for that DIC?
I tried but I came up short, the only one I could find was for a 90 GP DIC which is slightly different (LCD vs. VFD)...If you can find one that'd be cool. -Jason
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08:09 PM
mattman134 Member
Posts: 643 From: Buford, Ohio Registered: Dec 2009
Here is what was near production. As usual, PMD spent all the money to develop this Rally Computer and at the minute the supplier was ready to ship the finished product to the plant, they cancelled the project. My sources tell me that there were pilot units at the Fiero Plant ready to install waiting for corporate to finalize the financial outlook of the option. Once again, the bean counters got involved and the option was never offered. Another issue I see is that engineering was still finalizing technical data as of February of 1985. In PMD timeline, this would have not been ready until MY1987.
It appears that the option code would have been UV4. Does the 86 Fiero described in this post have the RPO UV4 on the SPI tag on the left fender well under the front decklid?
I do not recall seeing this computer in another GM car. Athough, I am sure the development cost might have went to another GM car.
Fred
I just checked my 86SE and the 86GT. both have the plug under the dash, but no UV4 code. My cars dont have the compass wiring either.
Matt
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08:33 PM
fierofool Member
Posts: 12811 From: Auburn, Georgia USA Registered: Jan 2002
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I don't think you would want to take it apart just for a pic...it was a pita and I didn't even have to put it back together....
