Pontiac Fiero 1988 Service Manual page 524

DRIVEABILITY A N D EMISSIONS - FUEL INJECTION (TBI) 6 E 2 - C 1 - 7
PROM
Code 51 indicates a faulty PROM, bent pins, or
incorrect installation.
[Y]
Important
It is possible to install a PROM backward. If the
PROM is installed backward and the ignition key
turned to "ON", the PROM circuitry will be destroyed,
requiring PROM replacement.
THE IGNITION SHOULD ALWAYS BE
I N S T A L L I N G
OR
R E M O V I N G
CONNECTORS.
pH^
R e m o v e or Disconnect
1. Connectors from ECM.
2. ECM mounting hardware.
3. ECM from passenger compartment.
4. ECM access cover (see Figure Cl-8).
5. PROM assembly. (Figure Cl-9).
"OFF" WHEN
THE ECM
Important
Using the rocker-type PROM removal tool, engage
one end of the PROM carrier with the hook end of
the tool (see Figure Cl-8). Press on the vertical
bar end of the tool and rock the engaged end of the
PROM carrier up as far as possible.
Engage the opposite end of the PROM carrier in
the same manner and rock this end up as far as
possible. Repeat this process until the PROM
carrier and PROM are free of the PROM socket.
The PROM carrier, with PROM in it, should lift
off of the PROM socket easily. PROM carrier
should only be removed by using the pictured
PROM removal tool. Other methods could cause
damage to the PROM or PROM socket.
Jff Inspect
1. New PROM for same part number as old.
Important
Do Not remove PROM from carrier to check
PROM number.
2. For correct reference of PROM in carrier, see
Figure Cl-10.
Install or C o n n e c t
1. New PROM carrier in PROM socket.
fT]
Important
Small notch of carrier should be aligned with
small notch in socket. Press on PROM carrier
until it is firmly seated in the socket. Do not press
on PROM; only the carrier.
2. Access cover on ECM.
1
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o
u
ax
ye
u u u u H I
L — —
[ T ] R E F E R E N C E END
pTI PROM
PH PROM C A R R I E R 4S 0465-6E
Figure CI-10 - PROM in PROM Carrier
3. ECM in passenger compartment.
4. Connectors to ECM.
Functional C h e c k
1. Turn ignition "ON".
2. Enter diagnostics.
A. Allow Code 12 to flash four times to verify no
other codes are present). This indicates the
PROM is installed properly and the ECM is
functioning.
B. If trouble Code 51 occurs, or if the "Service
Engine Soon" light is on constantly, with no
codes, the PROM is not fully seated or is
defective.
• If not fully seated, press firmly on the ends
of the PROM carrier.
• If it is necessary to remove the PROM,
follow the previous removal instructions.
|T"| Important
Any time the PROM is installed backward and the
ignition switch turned "ON", the PROM is
destroyed.
C O O L A N T SENSOR
Important
Care must be taken when handling coolant sensor.
Damage to coolant sensor will affect proper
operation of the Fuel Injection system.
4»»
R e m o v e or Disconnect
1. Relieve coolant pressure.
2. Negative battery cable.
3. Electrical connector.
4. Carefully back out coolant sensor.