1985-1998 [Subscribe to Daily Digest] |
The 78390 code means that the ETS ECU has determined that the throttle body is faulty... and it sounds like that's the only TCS-related component that you have not replaced yet.
Fault Codes 6/78390 (Malfunction In Throttle Valve Control)
1) Check if other fault codes are present. If other fault
codes are present, repair those fault codes first. If other codes are
not present, go to next step.
2) Check for leaks in vacuum circuit by starting engine.
Disconnect hose between non-return valve and intake manifold. If this
causes arm on throttle housing to retract, there is a system leak. To
pinpoint leak, pinch hoses, one at a time, from non-return valve via
safety valve to throttle housing. Replace any components that may be
causing leak.
3) If a leak is not present, raise vacuum in throttle housing
vacuum unit to release spring. In addition, disconnect intake boot at
throttle housing so throttle valve can be moved by hand.
4) Ensure ignition is off. Disconnect ETS ECU connector.
Measure resistance between ETS ECU connector terminals No. 20 (Green
wire) and No. 21 (Green/White wire). Move throttle valve slowly
through its entire travel. Stop throttle valve at several points so
resistance reading can stabilize. Resistance should be less than 200
ohms. If resistance is within specification, go to step 6). If
resistance is at any time greater than 200 ohms, go to step 5).
NOTE: It is normal for resistance to increase greater than
specification while motor is rotated. This is because of
brushes moving along the commutator. Compare resistance to
specification only with throttle valve held stationary.
5) Disconnect throttle housing connector. Measure resistance
of motor between throttle housing terminals No. 1 (Green wire) and No.
7 (Green/White wire). If resistance was greater than 200 ohms in step
4) but is to specification now, check and repair wiring as necessary.
If resistance was too high in both tests, replace throttle housing.
6) Check Green wire between throttle housing terminal No. 1
and ETS ECU terminal No. 20 for an open or short circuit. Also check
Green/White wire between throttle housing terminal No. 7 and ETS ECU
terminal No. 21 for an open or short circuit. If wiring is okay and
fault code persists, replace ETS ECU.
posted by 70.39.176...
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