SECTION 21

INSTRUMENTATION

1.0 Specification

Instrumentation Interface Module (IM)

1.1 Introduction

The purpose of the Instrumentation Interface Module (IM) is to provide a means of monitoring and/or modifying system operation to facilitate development This document will describe the application of the IM to this system.

1.2 Electrical Interface

The IM will access 12 volt battery, 12 volt ignition and power ground by means of a 3-pin connector. Interface to the ECM is made by means of a 50-pin connector attached to the GBAM (General Buffer Auxiliary Memory). This interface operates as a continuation of the ECM address, data and control bus structure.

1.3 Data Display

ECM data is displayed on a Heads-Up-Display (HUD) unit which will have the capability to be mounted on the vehicle dashboard remote from the IM mainframe.

Four digital displays are available; each composed of three, seven segment display devises with a right-hand decimal point. Eight discrete indicators are suitable for function status indicators, with a switch selection for a total of sixteen status flags.

1.3.1 Dedicated Digital Displays

Two of the four digital displays are dedicated to displaying onlv one parameter at all times. The top left-hand display will always display engine speed in revolutions per minute (RPM). The bottom left-hand display is available to display Manifold Absolute Pressure (MAP) in units of kilopascals.

When the engine speed is less than 1000 RPM, the respective display value has "units" resolution of speed. When the engine speed is greater than 1000 RPM, the display value has "tens" resolution.

1.3.2 Selectable Digital Displays

The two displays to the right of RPM and MAP are controlled by a ten position rotary selector switch to the right of the respective display and a "Cal A/B" switch.

Display "A" (Cal A) Selector Switch Information

Display "A" Selector Switch (Upper and Lower) Positions

0 1

9 2

8 3

7 4

6 5

Upper Switch Position Display Function Table

Position Display Parameter Label

0 Spark Advance (Degrees) SATDC

1 Barometric Pressure (kPa) ADBARO

2 Engine Coolant Temperature (Degrees C) COOLDEG

3 Manifold Air Temperature (Degrees C) MATDEG

4 IAC Present Motor Position (Steps) ISSPMP

5 Data Change Slew Value IDATAMOD

6 RAM Address Slew Value IADORMOD

7 Vehicle Read Speed (KPH) FILTMPH

8 A/F or Base Pulse Change Slew Value IAFMOD

9 Block Learn Multiplier BLM

Lower Switch Position Display Function Table

Position Display Parameter Label

0 Spark Advance Chanqe-Slew Value ISPKMOD

1 Knock Spark Retard NOCKRTD

2 Closed Loop Integrator Value INT

3 Wastegate Duty Cycle (percent) WGATEDC

4 IAC Desired Motor Position (Steps) IMPMOD

5 Base Pulse Width (Msec) BPW

6 Contents of RAM Location CONTENTS

7 Throttle Angle (Percent) NTPSLD

8 A/F Ratio AIRFUEL

9 EGR Duty Cycle (Percent) EGRDC

Display "B" (Cal (B) Selector Switch Information Display "B" Selector Switch (Upper and Lower) Positions

0 1

9 2

8 3

7 4

6 5

 

Upper Switch Position Display Function Table

Position Display Parameter Label

0 Average MPG MPGMEAN

1 Power Steering Stall ISALPA

2 Cold Control IAC Bias For P/N NBIASPN

3 IAC Drive Motor Position, Warm With No A/C ISWNAC

4 Manifold Absolute Pressure MAPP

5 IAC Drive Motor Position, Warm With A/C ISWWAC

6 Filtered RPM ISES

7 Battery Voltage ADRAT

8 FAN On Time FAN

9 Filtered O2 Value (A/D Counts) ADO2AFSC

Lower Switch Position Display Function Table

Position Display Parameter Label

0 IAC Extended Throttle Cracker With No A/C ETCACOFF

1 Coolant Offset for IAC ISMPTV

2 Cold Control IAC Bias For Drive NBIASDR

3 IAC P/N Motor Position, Warm With No A/C ISWNACP

4 IAC Desired Motor Position ISDSMP

5 IAC P/N Motor Position, Warm With A/C ISWWACP

6 Desired Engine Speed (RPM) DESSPD

7 Instantaneous MPG MPG

8 Delay Counter For P/S Crack Decay PSTCLC

9 IAC Extended Throttle Cracker With A/C ETCACON

1.3.3 Discrete Indicators

Eight discrete indicators located below the digital displays on the HUD are used to display ECM function status. The indicators are selectable between Status I and Status 2 by means of a toggle switch located to the left of the indicator lights. Each mode shall represent a group of eight discrete function indicators. The indicators individual functions are listed below. The indicators will be listed in order from left to right as they appear on the HUD. The lights will be lit if the statements are true.

Discrete Status Word Display Information (Display "A") Discrete Display of Status Word

Status #1

NVM BLM BKR TCC FAN AC PFM ACC

37 S6 55 54 33 32 51 50

Status #2

IAC ASYNCH LE AE DE PE CL R

Status Word #1 Display Information

Position Status Information

57 Non-Volatile Memory Failure

S6 BLM Cell

S5 BST Knock Reduction Activity

S4 TCC Enabled

S3 Fan

S2 Air Conditioning Request

S1 Premium Fuel Mode

S0 Air Conditioning Clutch Disabled

Status Word #2 Display Information

Position Status Information

S7 IAC Motor Moving

S6 Asynch Pulse Mode

S5 Learn Enabled

S4 Acceleration Enrichment

S3 Decel Enleanment

S2 Power Enrichment

S1 Closed Loop Enabled

S0 Oxygen Sensor RICH

Discrete Status Word Display Information (Display "R") Discrete Display of Status Word

Status #1

IN FAN FAN ISM IPCM ITC SSM ICC

GEAR ANT

S7 S6 S5 S4 S3 S2 S1 S0

Status #2

FO ESC ESC EGR EGR/VAC bB VM R

OPT ACT TIPIN

Status Word #1 Display Information

Position Status Information

S7 In Gear

S6 Fan On

S5 Fan Anticipated Mode

S4 IAC SAG Mode

S3 IAC PS Crank Mode

S2 IAC Throttle Crank

S1 Stall Saver Mode

S0 IAC Cold Control

Status Word #2 Display Information

Position Status Information

S7 Fuel Determination Disable

S6 ESC Option

S5 ESC Active

S4 EGR Tipin

S3 EGR VAC Switch Closed

S2 Limit Boost 1st TM

S1 Vehicle Moving

S0 Rich O2 Sensor

1.3.4 Display Control

All elements of the digital display will be updated with information at the control of the ECM This is primarily at integral multiplies of the ECM major loop time to prevent display jitters. In the event the operator desires a "snap shot" of displayed digital data, the switch labeled CONT/HOLD is used.

1.4 Analog Recording

The IM provides interface to the D/A module which has eight channels of analog data for strip chart recording purposes. Data from the ECM is selectable from the hand held 0/A unit and directed to any one of the eight analog output channels. These analog signals are Output via BNC connectors mounted on the 0/A chassis. The analog output has the following electrical characteristics:

Range 0 to 5 volts

Bandwidth 100 cycles/second

Resolution 19.6 mV/bit

1.4.1 Recording Channel/Parameter Selection

To enable the 0/A to update a channel, the thumbwheel selector switch should be moved to channel eight and address 5000 entered by rotating the address thumb wheel selector switches to 5000 and pushing the enter button.

If a scaling PROM has been installed in the D/A main frame the ootioo exists of outputting the specific parameters listed in Table 1.4.2. This is done by switching the left most toggle switch to "Scaling PROM" then entering the desired channel output (0-7) and desired parameter channel numbers in the address windows. Always hit the enter button for each channel used after entering channel number and parameter channel.

When other parameters are wanted to be viewed switch the channel to desired Output number and enter address in the address section, hit enter. With channel 7 any address may be output (0000-FFFF) channels 0-6 are limited to the first 2K block. Be sure to set the left most switch to 1 Byte or 2 Byte depending on the parameter wanted when in this mode.

1.4.2 Parameter Selection for HUD Meter Viewing

The two digit decimal thumb wheel selector switch assembly on the HUD specifies one of 41 parameters within the ECM function for viewing on the HUD analog meter. Listed below are the available parameters and corresponding channel numbers.

Analog Channel Assignments

Min. Max.

Block Parameter Scale Scale

0 Spark Advance 10 Deg. 60 Deg.

1 Barometric Pressure 0 KPa 105 kPa

2 Coolant Temperature -40 Deg. 152 Deg.

3 Oxygen Sensor Voltage 0 mV 999 mV

4 Volumetric Efficiency 0 Counts 255 Counts

5 Data Change-Slew Value -- --

6 RAM Address-Slew Value -- --

7 Vehicle Road Speed (MPH) -- --

8 A/F or BPW Slew Value 0 25.5

9 Block Learn Multiplier 0 Counts 255 Counts

10 Spark Advance Slew Value 0 Deg. 90 Deg.

11 Not Used

12 Closed Loop Integrator 0 Counts 255 Counts

13 Block Learn Cell 0 Counts 12 Counts

14 IAC OMP Slew Value 0 Counts 255 Counts

15 Base Pulse Width 0 mSec 0 mSec

Analog Channel Assignments (Continued)

Min. Max.

Block Parameter Scale Scale

16 IMMW3 (Octal) -- --

17 TPS Load 0% 100%

18 Air/Fuel Ratio 0 A/F 25.5 A/F

19 Battery Voltage 0V 25.5V

20 INNW1 0V 25.5V

21 IMMW2

22 RPM 0 RPM 5400 RPM

23 Manifold Absolute Pressure 10.35KPa 104.4KPa

24 Closed Loop Correction -- --

25 IAC Present Motor Position

26 Not Used

27 Not Used

28 Not Used

29 Not Used

30 Vehicle Road Speed (MPH) 0 KPH 200 KPH

31 Base Pulse Width 0 msec 100 msec

32 IMMW1B

33 IMMW2B

34 RPM 0 RPM 3200 RPM

35 RPM (Filtered) 0 RPM 1600 RPM

36 Base Pulse Width 0 msec 200 msec

37 IAC Present Motor Position 0 Counts 200 Counts

38 Manifold Air Temperature -40 Deg. 152 Deg.

39 A.E. Delta MAP 0 kPa 100 kPa

40 A.E. Delta Throttle 0% 100%

41 D.E. Delta MAP 0 kPa 100 kPa

42 D.E. Delta Throttle 0% 100%

43 N/V Ratio for Shift Light 0 Ratio 144 RA

44-100 Not Used

Since the introduction of the 0/A module, the single-digit decimal thumb wheel selector has no control over the Analog Output Channels. No matter what channel (1-5) the thumb-wheel is on you may only view on the analog meter on the HUD one of the variables listed above. The variables for viewing are still selected by the parameter selection switches.

1.5 ECM Function Modification

A group of eight control switches provide ECM function modification during operation. This function requires ECM functional requirements not covered by this specification.

1.5.1 Spark Change

The spark advance angle can be modifiable by the IM

When the bottom digital display selector switch is positioned to "spark advance change", a value is displayed which can be incremented or decremented in a continuous manner by the slew switch under the "spark" label. This value will be either combined with the ECM computed value or substituted for the ECM computed value based upon a front panel control switch labeled "ABS/NORM/MOD" under the "spark" label.

1.5.2 Air/Fuel Ratio Change

The air/fuel ratio can be modifiable by the IM

When the top digital display selector switch is positioned to "A/F change", a value is displayed which can be incremented or decremented in a continuous manner by the slew switch labeled "air fuel/Function A". This value will then either be combined with the ECM computed value, or substituted for the ECM computed value based upon a front panel control switch labeled "ABS/NORM/MOD" under the "Air Fuel/Function A" labeled region.

1.5.3 IAC Motor Position Change

The idle air control motor position can be controlled directly by the IM

When the bottom digital display selector switch is positioned to the "IAC change" position, a value is displayed which can be incremented or decremented in a continuous manner by the slew switch labeled "idle speed/Function B". This value will then either be combined with the ECM computed value, or substituted for the ECM computed value based upon a front panel control switch labeled "ABS/NORM/MOD" under the "idle speed/Function B'" labeled region.

When a negative value is placed in the slew and the ABS mode selected, an IAC Motor Reset will be performed.

1.5.4 RAM Address Change (Function B)

The IM has the capability to display the contents of each ECM RAM cell. Thi3 is accomplished by placing the top digital display selector switch in the "RAM address" position and the bottom digital display selector switch im the "RAM contents"' position. The selector switch under the "Function B" heading must also be in the "B" position.

The RAM address may then be incremented or decremented by using the "Function B slew" switch, and the RAM contents can be observed in the bottom right-hand digital display.

1.6 IM Subroutines

Software routines in the ECM program which are dedicated to supporting the IM are written in the form of subroutines and located in EPROM’s physically located in the GBAM hardware. In operation, the ECM will perform a test at power-up initialization to determine if an IM is present. If the test is positive, the ECM will transfer program control to the IM subroutines in the IM at appropriate times to perform IM functions. The purpose of this feature is to minimize the IM software overhead in production programs.

1.7 Miscellaneous Controls

The functional controller of the IM will be reset by the "RESET" switch independent of the ECM controller. The reset state will enable all display segments and status bits as well as turning on the HUD fail indicator.

1.8 Environmental Considerations

Normal operating temperature of the IM is 40C to 85C. This constraint is imposed because of operating temperature characteristics of the EPROM memory modules.