Hi im doing a custom C5 gauge conversion in my Fiero and i have some questions about the c5 gauges i figured this would be the right place to ask!! From what i understand the PCM takes the resistance values of the sender units converts them and sends them to the gauges..
My first question would be what would be the converted values that the PCM produce's for the fuel,temp,amp, and oil gauges?

 

I could use some wiring diagrams too of the pcm to the instrument cluster!

 

Well, first I think you should be talking about the BCM, not the PCM. What year is the IPC from? I'll find you a schematic.
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Sorry bout that, most of tha info comes from the PCM.

 

I seem to remember reading that the oil pressure sender outputs info digitally. It actually has a built-in analog to digital converter built in on a small IC.

This might be more complicated than you think!

 

The "Class 2 Digital" signals will be a challenge, in my opinion. Good Luck!
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Instrument Panel Cluster (IPC) Description and Operation
Displays Test
Certain instrument panel cluster (IPC) features are tested when the ignition is turned on in order to verify the features are working properly. The following occurs at key up:

The air bag indicator flashes 7 times.
The ABS indicator illuminates briefly.
The check engine indicator (MIL) illuminates briefly.
The brake indicator illuminates briefly.
All gages sweep.
The HUD illuminates all segments briefly.
The security indicator illuminates briefly.
The check gages indicator illuminates briefly.
The traction indicator illuminates briefly.
The seat belt indicator illuminates.
The MPH or KM/H indicator illuminates.
The DIC displays CORVETTE BY CHEVROLET briefly and then it will display the last item before key off.
The audible warning chimes 6 times.
Indicators and Warning Messages
Refer to Indicator/Warning Message Description and Operation .

Engine Coolant Temperature Gage
The IPC displays the engine coolant temperature as determined by the PCM. The IPC receives a class 2 message from the PCM indicating the engine coolant temperature. The engine coolant temperature gage defaults to 215°C (260°F) or below if:

The PCM detects a malfunction in the engine coolant temperature sensor circuit.
The IPC will display the engine coolant temperature message on the DIC.
The check gages indicator turns on.
Engine Oil Pressure Gage
The IPC displays the engine oil pressure as determined by the PCM. The IPC receives a class 2 message from the PCM indicating the engine oil pressure. The engine oil pressure gage defaults to 0 kPa (0 psi) or below if:

The PCM detects a malfunction in the engine oil pressure sensor circuit.
The IPC will display the low oil pressure message on the DIC.
The check gages indicator turns on.
Fuel Gage
The IPC displays the fuel level as determined by the PCM. The IPC receives a class 2 message from the PCM indicating the fuel level percent. The fuel gage defaults to empty if:

The PCM detects a malfunction in the fuel level sensor circuit.
The IPC displays a low fuel message on the DIC.
The check gages indicator turns on.
Speedometer
The IPC displays the vehicle speed based on the information from the vehicle speed sensor. The PCM converts the data from the vehicle speed sensor to a 4000 pulses/mile signal. The IPC uses the vehicle speed signal circuit (4000 pulses/mile) from the PCM in order to calculate the vehicle speed. The speedometer defaults to 0 km/h (0 mph) if a malfunction in the vehicle speed signal circuit (4000 pulses/mile) exists. The speedometer displays either miles or kilometers as requested by the activation of the English/metric button on the driver information center (DIC). The associated indicator (MPH or KM/H) illuminates.

Tachometer
The IPC displays the engine speed as determined by the PCM. The IPC receives a class 2 message from the PCM indicating the engine speed. The tachometer will default to 0 RPM if the PCM detects a malfunction in the engine speed sensor circuit.

Voltmeter
The IPC displays the system voltage as detected at the ignition 1 input of the IPC. The voltage on the volt gage is also displayed on the DIC. The IPC displays high or low voltage on the DIC when the IPC detects voltage levels out of range.

 

That is what I'm thinking. Not Digital from the Sender, but Digital from the PCM to the IPC. (I think.)

 

The meter movements themselves are analog. Assuming you can access the actual meter inputs, you might be able to correct with resistors...

 

wow thanks for the info!! yeah the IPC is a 1999+ hud ready model.
Okay so there's another computer in the IPC that translates the "class 2 digital" signal from the PCM then to the analog gauges?
So would that mean that the analog gauges in the IPC would all have the same resistance range? anyone know what that would be?

 

i just checked the year on my IPC its a 2003! i could use the wiring diagrams for it so i know what wires go where
thanks you!!

 

 

thanks for the diagrams!!!! looks like the speedometer, and the voltmeter, dont use the class 2 signal... so im going to have to modify the tach, oil, temp, and fuel gauges... i might be able to take the board out of a 4cyl/v8 tach and modify it to work with the tach in the IPC and i will have to find out the resistance of the other gauges and then put resistors inline from the fiero senders..
anyone have any other ideas?

 

 

still waiting on some plugs and stuff i will post some pics when i get cracking on this thing!!!

 

Excellent info guys. Not wanting to hijack this thread and mine is a C6 cluster conversion question anyway so I will post in that sectionalso but definitely wanted to get the attention of those knowledgeable folks reading this thread.

I have an LS7 w/T56 retrofitted into a '69 Camaro. I'll be getting a custom harness made (several places make them to order). I am running the stock E38 ECU (reprogrammed). I wish to use a C6 cluster which I have here and make the most use of all the lamps and gauges as possible (except airbags). Trouble is - I have no connectors or wiring for the back of the cluster. There is one built-in pigtail with a connector on it and then two additional connector ports.

Can anyone provide the information I need to put this together? Do I need any other control modules, fuses etc? I have most if not all the stock sensors on both the LS7 and the F-Body T56 itself.

The people I am speaking to about the harness are saying they can provide the signal wires out of the ECU that I might need but they do not have experience with the actual cluster end of things.

Dumb question: Is the "PCM" a different name for the "ECU" or is it a different module altogether?

Any assistance appreciated.
Thanks guys,
G.

 

well so far iv been having trouble getting a plug for the cluster...
does anyone have a color code diagram or anything for the main plug on the back of the cluster? i might be able to go off of the pins them self's for testing till i get a plug

 

This look like it?
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Connector Part Information
12065803
34-Way F Micro-Pack 100 Series (BLK)

Pin
Wire Color
Circuit No.
Function

A1
--
--
Not Used

A2
LT GRN
11
Headlamp High Beam Supply Voltage

A3
WHT
103
Headlamp Switch Headlamps On Signal

A4
BLK/WHT
99
Windshield Washer Fluid Level Signal

A5
--
--
Not Used

A6
TAN/WHT
33
Brake Warning Indicator Control

A7
DK GRN/WHT
817
Vehicle Speed Signal

A8
BLK
150
Ground

A9
--
--
Not Used

A10
DK GRN/WHT
357
Oil Temperature Sensor Signal

A11
GRY
1036
IPC Class 2 Serial Data

A12
--
--
Not Used

A13
PNK
139
Ignition 1 Voltage

A14
ORN
1640
Battery Positive Voltage

A15
LT BLU
14
Left Turn Signal Status Signal

A16
DK BLU
15
Right Turn Signal Status Signal

A17
WHT
121
Engine Speed Signal

B1
--
--
Not Used

B2
BLK/WHT
238
Seat Belt Switch Signal -- Driver

B3
--
--
Not Used

B4
PPL
333
Brake Fluid Level Sensor Signal

B5
WHT
717
Illuminated Display Signal

B6
GRY/BLK
1458
Instrument Panel Lamp Supply Voltage - 4

B7
--
--
Not Used

B8
BLK
470
Low Reference

B9-B10
--
--
Not Used

B11
WHT
375
Skip Shift Indicator Control

B12
--
--
Not Used

B13
BLK/WHT
851
Ground

B14
--
--
Not Used

B15
BLK
150
Ground

B16
BRN/WHT
419
MIL Control

B17
BRN
9
Park Lamp Supply Voltage

 

ALRIGHT!!!! now i can get down to business haha Thanks!!