I'm looking to better fill in some of the ambiguities in the pinouts of the C500 connector on the 85-87 Fieros.

1) I know some small differences exist even among these years but I don't know what they are off the top of my head nor do I remember where the information on this was. I was hoping somebody could either share these differences or list specific pinouts if available aside from the generic ones we see posted all of the time?



2) Also, I've noticed some differences in what I find posted from the 86 service manual and what I pulled from it directly:

From the 86 Service manual I pulled this pinout



Yet in some threads I'm finding this pinout posted but never a really definitive source being listed for it except the 86 Service manual but its obviously not the exact same pinout as I posted above.




3) Please feel free to share any similar information related to the C203 as well if desired.

Both charts are correct, however, not for all models of the Fiero.

For instance, pre 86 had the trunk ajar circuit triggered by a contact switch on a bracket on the left rear of the trunk compartment, whereas the 86 and up had the switch integrated into the trunk latch. The C-500 pinouts reflect this, as prior to 86, the circuit passed through the C-500.

Automatic and manual cars are different as well, due to the inclusion of the Neutral Safety Switch. 86 and up GT's are different due to the 'PONTIAC' in the tail light panel.

Ryan at Sinister Performance www.gmtuners.com has pinouts of the C-500 and the C-203 in the Tech section.

Perhaps the best advice I can share on this topic is to look at the pinning on the car you are working on, look at the pinout info, and then determine what is applicable to your situation.

I hope this info helps you out.

Joe

Edited to correct statement.

[This message has been edited by olejoedad (edited 03-20-2012).]

On C500 the light green wire to the back up lights does not exist on the body harness going forward for Automatic cars. This is regardless of year.

Thanks for the input though unfortunately a lot of it isn't particularly new to me.

quote Originally posted by olejoedad: Both charts are correct, however, not for all models of the Fiero.

I agree. I'm interested in why the charts are different though if they supposedly came from the same source. Is another source known for the second chart? Practically it doesn't matter but I'm interested nonetheless.

quote Originally posted by olejoedad: For instance, pre 86 had the trunk ajar circuit triggered by a contact switch on a bracket on the left rear of the trunk compartment, whereas the 86 and up had the switch integrated into the trunk latch. The C-500 pinouts reflect this, as prior to 86, the circuit did not pass through the C-500.

This is the kind of information I was looking for so thanks! I was aware the 84 Fieros were wired this way but was unsure when the change was made.

quote Originally posted by olejoedad: 86 and up GT's are different due to the 'PONTIAC' in the tail light panel.

Is there any more specific information available on this? I believe I've read in the past that its only a difference of a wire but I could be wrong. Do both taillight wiring options remain unchanged in all 86-88 Fieros?

quote Originally posted by olejoedad: Ryan at Sinister Performance www.gmtuners.com has pinouts of the C-500 and the C-203 in the Tech section.

Yes, I have a copy of his pinout. Its makes an attempt at being a comprehensive pinout for various years but its incomplete in doing so.

quote Originally posted by olejoedad: Perhaps the best advice I can share on this topic is to look at the pinning on the car you are working on, look at the pinout info, and then determine what is applicable to your situation

I agree. I was just hoping to create a better and more detailed source of information for quick reference. I'm not actually working on any car in particular at the moment. Its easy to check to see if a particular car is wired the way you believe it is but having a dependable source for information is always nice as well.

quote Originally posted by olejoedad: I hope this info helps you out.

Thanks for sharing what you have so far

[This message has been edited by GraterFang (edited 03-16-2012).]

quote Originally posted by olejoedad: For instance, pre 86 had the trunk ajar circuit triggered by a contact switch on a bracket on the left rear of the trunk compartment, whereas the 86 and up had the switch integrated into the trunk latch.

My experience indicates that it wasn't specifically the '86 model year that introduced this so much as it was the fastback design. The reason I say this is because my first '86 SE V6 notchback had the pin switch on the bracket, not the integrated latch switch.

Other observations I've gleaned from experience for the '86 model year:

Pin J8 should be labelled RT Turn, not Turn/Stop
Pin H7 should be labelled LT Turn, not Turn/Stop
Pin G9 is used for the PONTIAC and engine blower relay on fastbacks, and for teh engine blower relay only on V6 notchbacks
H9 is shown in the wire diagrams to be a green/wht wire used with the engine blower circuit not an oragne wire used for "Lights: Turn/Stop"
G7 and H8 are used for stop lights on notchbacks and is a white wire, but G7 only is used on fastbacks where the chassis half of the wire is white, and the tail lamps half is light blue.
J9 is not used for stop lamps on '86's regardless of body style, though it may be used on later years rather than G7.

Lots of good info.

My 86 SE has the switch on the latch, maybe an Option Group change? My SE was pretty decked out.

quote Originally posted by Bloozberry: My experience indicates that it wasn't specifically the '86 model year that introduced this so much as it was the fastback design. The reason I say this is because my first '86 SE V6 notchback had the pin switch on the bracket, not the integrated latch switch.

quote olejoedad: My 86 SE has the switch on the latch, maybe an Option Group change? My SE was pretty decked out.

I would guess this is just another one of those things that didn't change precisely at a model year boundary. Bloozberry's 86SE is probably an older serial than olejoe's.
I bet in reality the majority of minor/unadvertised design changes didn't happen exactly at a model year, though they usually end up being thought of that way. Like many things it probably just changed when it was convenient and all the old parts were used up.
Generalities like "model year X has design Y" often aren't 100% reliable statements IMO, but hold true more like 95% of the time.

Interesting topic. My very early (Sept 85) 86SE has the switch in the latch, I know our 85 SE doesn't, it has the pin switch.

Also, I believe olejoedad had it backwords, because my 85 SE has the trunk release wire goes though the C500 (Pin A1, Blk) while my 86 SE does not, it tees off from the body harness before the C500 to a 4 pin connector on the decklid itself, for the latch.

Edit: I'm seeing a pattern between having the pin switch and having the trunk release wire go though the C500 or not.

[This message has been edited by mattwa (edited 03-18-2012).]

Figured I would bump this thread to see what else might be contributed

Good catch Mattwa, I said it backwards.

Edited previous post.

Bump as I am going through this today on my 86 GT fastback.

Bump.

Can anyone verify the temp guage pin from C203? does the temp guage on the dash even run through C203? My temp gauge is dead after a 3800sc swap, I have the updated 3pin temp sensor. The rad fan works, and my scan gauge gives an accurate temp reading.

On Ryans website: ( http://www.gmtuners.com/fil...203_C500_pinouts.pdf )

PIN C2 on the C500 connector is a "temp guage sender feed" But in the previous post above C2 = "indicators"

Well it does not run through C203.

Stock is

C500 C2 for the Temp Gauge
C500 D3 for the Temp Light

They may be reversed however. To test - Key on engine off - ground the wire. If the temp light comes on then the wire you are looking at is for the light. If instead it is for the gauge the temp gauge will peg hot.

How to reverse the functions of the wires at the dash (and eliminate the pegging of the temp gauge at start up)
http://www.fierosails.com/tempgage.html

quote Originally posted by phonedawgz: Well it does not run through C203. Stock is C500 C2 for the Temp Gauge C500 D3 for the Temp Light They may be reversed however. To test - Key on engine off - ground the wire. If the temp light comes on then the wire you are looking at is for the light. If instead it is for the gauge the temp gauge will peg hot. How to reverse the functions of the wires at the dash (and eliminate the pegging of the temp gauge at start up) http://www.fierosails.com/tempgage.html

Very useful link, thank you. Ground green wire at temp senor = temp light on dash. No action when I grounded the other two. Temp gauge pegs at start up, and stays at 40 when eng on. Must be bad wire or connection somewhere, I will start investigating. Sorry for threadjacking, maybe this will help someone else out.