Having problems with your 1990 Lexus LS 400 ?

Rpm rev up and down in idle

\015 I replaced the camshaft sensor and mass air flow sensor and code 13 is still coming up tachometer is rev up and down in idle and in drive at idle\015 Posted / edited by AnonymousUser on : 16-07-2018

Answers :

The RPM signal comes from the crank sensor. The harness connector needs \012to be checked for a 5v reference signal and the ground side needs to be \012checked for a good ground. This test is to rule out the computer as \012being the issue. Then the signal wire needs to be checked for a good \012signal. When the crank sensor fails you get not spark and no fuel., \012You will need a waveform viewer to determine if the sensor has failed.
\012You will need a basic meter to determine if the computer has failed.
Repair Help & Product Troubleshooting for 1990 Lexus LS 400

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