Chapter 7
Geo
This chapter contains information for testing Geo vehicles with the Asian Import Vehicle
Communication Software (VCS). The following Geo systems may be available for testing:
• Engine
• Transmission
• Antilock Brake System (ABS)
7.1 Testing Engine, Transmission, and Antilock Brake
Systems
i
NOTE:
Operations described in this section are not available on all tool platforms.
Geo engine, transmission, and antilock brake system testing includes:
•
•
•
•
•
“Code Reading Connectors and Locations” on page 53
“Hard Codes and Soft Codes” on page 61
“Clearing Codes” on page 61
“Field Service Functional Tests” on page 61
“Prizm Actuator Tests” on page 62
7.1.1 Code Reading Connectors and Locations
Code reading test connector location, procedure, and adapter use varies by model.
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To read 1989–95 Prizm engine codes:
• Connect the TOY-1 adapter to the connector in the box marked “diagnosis” on either
fenderwell (Figure 7-1).
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Chapter 7 Geo
Testing Engine, Transmission, and Antilock Brake Systems
A
B
Figure 7-1 1989–95 Prizm connector location
A—Connector
B—TOY-1 adapter
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To read 1989–95 Prizm engine codes (optional):
• Jump diagnosis connector pins as shown in Figure 7-2.
A
B
Figure 7-2 Jump pins for flash codes
A—Terminal E1
B—Terminal T, TE, or TE1
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To read 1989–92 Metro (except 1992 1.3L) engine codes:
• Connect the MULTI-1 adapter with red terminal converters to the connector near the left
side of the engine (Figure 7-3).
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A
C
B
D
E
Figure 7-3 1989–92 (except 1992 1.3L) connector and adapter
A—Connector
B—MULTI-1 adapter
C—Green
D—White
E— Black
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To read 1989 Spectrum and 1990–94 Storm engine codes:
• Connect the MULTI-2-D adapter to the connector near the passenger kick panel
(Figure 7-4).
A
B
C
Figure 7-4 1989 Spectrum and 1990–94 Storm connector and adapter
A—Connector
B—MULTI-2 adapter
C—MULTI-2-D
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To read 1989 Spectrum and 1990–94 Storm engine codes (optional):
• Jump pins as shown in Figure 7-5.
Figure 7-5 Pins to jump for flash codes
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Chapter 7 Geo
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Testing Engine, Transmission, and Antilock Brake Systems
To read 1989–95 Tracker engine codes:
• Jump pins as shown in Figure 7-6 on the connector near the left side of the engine.
Figure 7-6 1989–95 Tracker connector jump pins
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To read 1992–95 Metro (except 1992 1.0L) engine codes:
• Jump pins as shown in Figure 7-7 on the connector near the left strut tower on the firewall.
Figure 7-7 1992–1995 Metro connector jump pins
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To read 1992–94 Storm 1.8L transmission codes:
• Connect the MULTI-1 adapter to the 5-pin connector under the glove box (Figure 7-8).
B
A
Figure 7-8 1992–94 Storm 1.8L connector and adapter
A—Connector
B—MULTI-1 adapter
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To read 1992–94 Storm 1.8L transmission codes (optional):
• Jump pins as shown in Figure 7-9.
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A
B
Figure 7-9 Pins to jumper for transmission codes
A—Red
B—Black
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To read 1992–95 1.3L and 1995 1.0L Metro transmission codes:
• Connect the MULTI-1 adapter to the 3-pin connector (Figure 7-10) under the left side of
the dashboard.
A
B
C
D
E
Figure 7-10 1992–95 1.3L and 1995 1.0L Metro connector and adapter
A—Connector
B—MULTI-1 adapter
C—Green
D—White
E— Black
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To read 1992–94 1.0L Metro transmission codes:
• Connect the MULTI-1 adapter as shown in Figure 7-11.
B
A
C
D
F
E
G
Figure 7-11 1992–94 1.0L Metro transmission connector and adapter
A—Diagnostic connector 701—pink wire and black/white wire
B—Diagnostic connector 705—black wire and pink/black wire
C—MULTI-1 adapter
D—Green
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Chapter 7 Geo
Testing Engine, Transmission, and Antilock Brake Systems
E— Steering column
F— Black
G—White
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To read 1992 Prizm with 4AGE and 1993–95 Prizm with 7AFE transmission codes:
• Connect the TOY-1 adapter to the connector shown in Figure 7-12.
A
B
Figure 7-12 1992 Prizm with 4AGE and 1993–95 Prizm with 7AFE transmission
A—Connector
B—TOY-1 adapter
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To read 1993–95 Prizm, 1992–95 1.3L Metro, and 1995 1.0L Metro Delco-Moraine VI
ABS codes:
• Connect the MULTI-1 adapter to the connector under the left dash (Figure 7-13 on
page 58).
A
B
C
F
E
D
C
B
A
G
H
J
K
L
M
D
Figure 7-13 1993–95 Prizm, 1992–95 1.3L Metro, and 1995 1.0L Metro ABS connector
A—Connector
B—MULTI-1 adapter
C—Black
D—Green
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To read 1990–95 Tracker Kelsey-Hayes RWAL ABS codes:
1. Locate the connector under the dash, left of the steering column near the fuse box.
2. Turn the key on with the engine off.
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3. Release the parking brake and jump pins 3 and 5 (Figure 7-14) for two seconds, then
remove the wire to flash codes.
Figure 7-14 1990–95 Tracker RWAL ABS connector jump pins
Manual Code Reading
Several different types of manual code display are used for Geo models:
•
•
•
•
•
Type 01 engine codes, see Figure 7-15 and Table 7-1 on page 59
Type 09 engine codes, see Figure 7-16 and Table 7-2 on page 60
Type 01 transmission codes, see Figure 7-17 and Table 7-3 on page 60
Type 09 transmission codes, see Figure 7-18 and Table 7-4 on page 60
ABS codes, see Figure 7-19
0.3 Sec.
On
1.0
Sec.
Off
3.0
Sec.
First
Digit (2)
Second
Digit (3)
Code 23
1
2
Code 12
Figure 7-15 Engine Code Type 01
Table 7-1 Engine Code Type 01
Pattern:
10s and 1s
Read codes on:
CHECK ENGINE lamp
Start codes by:
Install a jumper wire between two pins and turn the ignition on.
When done:
Turn the ignition off, remove jumper wire, then clear codes.
Code 12 always appears first. Each code repeats three times, including code 12. The code display
cycle repeats as long as system is in a diagnostic state.
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Chapter 7 Geo
Testing Engine, Transmission, and Antilock Brake Systems
0.5 Sec.
On
Off
1.5
Sec.
2.5
Sec.
First
Digit (2)
Second
Digit (3)
1.5
Sec.
4.5
Sec.
1
Code 23
2
Restart
Code 12
Figure 7-16 Engine Code Type 09
Table 7-2 Engine Code Type 09
Pattern:
10s and 1s
Read codes on:
CHECK ENGINE lamp
Start codes by:
Use TOY-1 adapter, turn the ignition on, and select Manual Codes.
When done:
Turn the ignition off, disconnect the scan tool, the clear codes.
0.3 Sec.
On
1.0
Sec.
Off
3.0
Sec.
First
Digit (2)
Second
Digit (3)
1
Code 23
2
Code 12
Figure 7-17 Transmission Code Type 01
Table 7-3 Transmission Code Type 01
Pattern:
10s and 1s
Read codes on:
ECONO lamp
Start codes by:
Connect the MULTI-1 adapter, turn the ignition on, and select Manual Codes, or
install a jumper wire between two pins and turn the ignition on.
When done:
Turn the ignition off, remove the jumper wire, then clear codes.
Code 12 always appears first. Each code repeats three times, including code 12. The code display
cycle repeats as long as system is in a diagnostic state.
0.5 Sec.
On
Off
1.5
Sec.
First
Digit (2)
2.5
Sec.
Second
Digit (3)
Code 23
1.5
Sec.
1
4.5
Sec.
2
Restart
Code 12
Figure 7-18 Transmission Code Type 09
Table 7-4 Transmission Code Type 09
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Pattern:
10s and 1s
Read codes on:
O/D OFF lamp
Start codes by:
Connect the TOY-1 adapter, turn the O/D switch on, turn the ignition on, then
select Manual Codes.
When done:
Turn the ignition off, disconnect the scan tool, then clear codes.
Geo ABS codes flash in a straight count with one long flash at the end (Figure 7-19). The code
repeats, only one code is stored.
Lamp On
Lamp Off
Code 4
Code 4
Figure 7-19 ABS diagnostic code pulse
7.1.2 Hard Codes and Soft Codes
Some models separate hard codes from soft (“historical”) codes (Figure 7-20).
RPM_1234 O2(mV)___689 MC DWL(°)__38
** DIAGNOSTIC MODE. DO NOT DRIVE. **
13 O2 SENSOR NOT WARM ENOUGH
HC HISTORICAL CODES FOLLOW
Figure 7-20 Data display with historical codes
7.1.3 Clearing Codes
Some 1987 and later models allow clearing trouble codes from the Exit menu (Figure 7-21).
RESUME
PRINT SCREEN
PRINT FRAME
ARM MOVIE
LED MENU
> CLEAR ECM CODES
FIX LINE 2
Figure 7-21 CLEAR ECM CODES
If the code-clearing operation fails for any reason, the previous codes reappear at the top of
the data list when you return to CODES & DATA. If this happens, repeat code clearing.
7.1.4 Field Service Functional Tests
i
NOTE:
Operations described in this section are not available on all tool platforms.
The Field Service functional test is available for most 1980½ and later Geo models with
General Motors control systems.
Selecting FIELD SERVICE displays a screen like Figure 7-22.
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Chapter 7 Geo
Testing Engine, Transmission, and Antilock Brake Systems
FIELD SERVICE - ALDL PINS 1 & B SHORTED
WITH KEY ON/ENGINE OFF, CE LAMP FLASHES
TROUBLE CODES, AND SOME ECM OUTPUTS ARE
EXERCISED. PRESS N TO EXIT.
Figure 7-22 Sample Field Service
IMPORTANT:
Do not enter Field Service mode while driving a vehicle. ECM changes to ignition timing, fuel
delivery, and other engine functions may affect engine operation and vehicle control.
During Field Service, the VCS grounds diagnostic pin B in the ALDL connector. The ECM
does not transmit data in this mode and new trouble codes cannot set. You can use FIELD
SERVICE to check or adjust ignition timing or the idle minimum air rate on some models.
With the key on and the engine off, the instrument panel CHECK ENGINE lamp flashes stored
trouble codes if any are present or code 12 if no codes are present. With the key on and the
engine off, the ECM also energizes all solenoids. You can use Field Service mode to test
solenoid operation.
Field Service mode works differently depending on the engine:
• With a carbureted engine running, the CHECK ENGINE LAMP stops flashing code 12 and
new trouble codes cannot be set. The ECM also sets ignition timing to a fixed degree of
advance, which lets you check and adjust timing. You also can use the Field Service
mode for a system performance check on carbureted engines. Refer to a vehicle service
manual for details.
• For some fuel-injected engines, the instrument panel CHECK ENGINE lamp flashes
rapidly when the engine is running in open loop and slowly when in closed loop.
Additionally, in closed loop, the length of the lamp flash indicates whether the exhaust is
rich or lean. The lamp flash is longer if the exhaust is rich.
7.1.5 Prizm Actuator Tests
The 1996 and later Geo Prizm offers interactive bidirectional actuator tests. Most of the
actuator tests are best performed with the key on and the engine running. The Fuel Pump and
Fuel Pump Relay tests must be performed with the key and engine off.
Most tests automatically display data parameters to help determine actuator or system
performance, but some tests do not display parameters and require you to monitor the
selected actuator. Measure the signal using a digital multimeter, or listen for activation. For
most tests, scrolling up and down switches the actuator on and off. Test completion does not
mean that the actuator was activated.
IMPORTANT:
Do not enter any actuator test while driving a vehicle on a road test, unless the specific test
requires you to do so. PCM changes to ignition timing, fuel delivery, and other engine
functions may affect engine operation and vehicle control.
For engine testing, selecting ACTUATOR TESTS displays the following menu (Figure 7-23).
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INJ VOLUME
>IAC DUTY RATIO
EGR SYSTEM
FUEL PUMP RELAY
FUEL PUMP
A/C CLUTCH RELAY
FUEL CUT PROHIBIT
TE1
Figure 7-23 Complete engine actuator test menu
For transmission testing, selecting ACTUATOR TESTS displays the following menu
(Figure 7-24).
>O/D CUT SOL
LOCK UP
SHIFT
Figure 7-24 Transmission actuator tests
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To perform an EGR system test:
1. From the ACTUATOR TESTS menu, select EGR SYSTEM.
A screen like Figure 7-25 displays.
BEFORE RUNNING TEST, ENSURE THAT
KEY IS ON AND ENGINE IS RUNNING
PRESS Y TO ACTIVATE TEST
Figure 7-25 Begin EGR SYSTEM test
2. Press Y.
A screen like Figure 7-26 displays.
EGR SYS____ON
EGR TEMP(°F)___97
ST TRIM B1(%)____12
ST TRIM B2(%)___0
SCROLL UP/DOWN TO TURN ON/OFF
PRESS N TO ABORT THE TEST
Figure 7-26 EGR test
3. Raise the engine RPM to 2500. By scrolling up and down, you control the PCM command
to the valve that switches sense vacuum to the EGR valve on and off.
The EGR TEMP and ST TRIM parameters on the screen make it easy to determine if
exhaust gas is indeed being recirculated.
– With EGR SYS___OFF, expect low EGR TEMP.
– With the EGR SYS__ON, the EGR TEMP should rise and the ST TRIM values
should change.
4. After testing the EGR, press N and this message displays (Figure 7-27).
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Chapter 7 Geo
Testing Engine, Transmission, and Antilock Brake Systems
EGR SYSTEM
TEST HAS BEEN COMPLETED
PRESS Y TO REPEAT TEST
PRESS N FOR ACTUATOR TEST MENU
Figure 7-27 EGR test complete message
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To perform a Fuel Pump test:
1. From the ACTUATOR TESTS menu, select FUEL PUMP.
A screen like Figure 7-28 displays.
BEFORE RUNNING TEST, ENSURE THAT
KEY IS ON AND ENGINE IS RUNNING
PRESS Y TO ACTIVATE TEST
Figure 7-28 Begin FUEL PUMP test
2. Press Y.
A screen like Figure 7-29 displays.
ACTIVATING FUEL PUMP
FOR 30 SECONDS
IN PROGRESS
PRESS N TO ABORT TEST.
Figure 7-29 Fuel Pump test
The IN PROGRESS flashes until the end of the 30-second period. After 30 seconds, the
pump shuts off and a screen like Figure 7-30 displays.
FUEL PUMP
TEST HAS BEEN COMPLETED
PRESS Y TO REPEAT TEST
PRESS N FOR ACTUATOR TEST MENU
Figure 7-30 Fuel Pump test complete message
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