Volvo RWD 700 Forum

INDEX FOR 10/2025(CURRENT) INDEX FOR 3/2019 700 INDEX

[<<]  [>>]


THREADED THREADED EXPANDED FLAT PRINT ALL
MESSAGES IN THIS THREAD




  REPLY TO THIS MESSAGE    PRINT   SAVE 

RPM Sensor 700 1989

posted by  ahunter on  Thu Oct 14 09:49 CST 2004
Author: [PROFILE] [EVERY POST] [THREADS] [BEST POSTS] RSS Feed     [IGNORE ALL POSTS]
last visit: Wed Jun 30 03:23 CST 2010
[RELATED]

Still trying to diagnose my intermittent no-start. Can someone explain to me what the RPM sensor does and why it would cause the ignition to fail.
--
1989 740GL 177k








  •   REPLY TO THIS MESSAGE    PRINT   SAVE 

    RPM Sensor 700 1989

    posted by  someone claiming to be j on  Thu Oct 14 10:27 CST 2004 [RELATED]

    sends pulse to ECU which is used to determine engine speed. ECU uses it to adjust IAC. No pulse=no start since the ECU won't ground the fuel pump side of Main relay without it.








    •   REPLY TO THIS MESSAGE    PRINT   SAVE 

      RPM Sensor 700 1989

      posted by  interstition on  Thu Oct 14 14:00 CST 2004
      Author: [PROFILE] [EVERY POST] [THREADS] [BEST POSTS] RSS Feed     [IGNORE ALL POSTS]
      last visit: Mon Apr 28 10:13 CST 2014
      [RELATED]

      And the reason the ECU won't energize the fuel pump relay without any signal from the RPM sensor is for safety. After an accident, if the engine isn't turning, but the fuel pumps are, it could be a very bad thing.
      --
      Andy in St. Paul, '91 745 Regina 198K mi, '89 244 141K, '87 245 RIP







<< < > >>



©Jarrod Stenberg 1997-2022. All material except where indicated.


All participants agree to these terms.

Brickboard.com is not affiliated with nor sponsored by AB Volvo, Volvo Car Corporation, Volvo Cars of North America, Inc. or Ford Motor Company. Brickboard.com is a Volvo owner/enthusiast site, similar to a club, and does not intend to pose as an official Volvo site. The official Volvo site can be found here.