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.