95 Saturn SL1 problem w/ fan, thermostat, and Back-up light

Discussion in 'Saturn S-series' started by Roger E, Jul 3, 2008.

  1. Roger E

    Roger E Guest

    Car: 1995 Saturn SL1 SOHC.

    Symptom 1: Temperature gauge reads temperature but engine is running
    cool. Temp Gauge below typical running temperature. About 2 minutes
    after car starts running the radiator fan starts and runs non stop for
    about 30 minutes then soon restarts or until ignition is off. Season is
    summer; environmental temp is about 27 deg Celsius. Typical drive is 60
    minutes duration. Engine is not overheating. No leaks in coolant
    system/hoses, reservoir level is good. Coolant mix is ethylene-glycol
    coolant with distilled water in a 70:30 ratio.

    My thoughts: From reading my Haynes manual, it appears the thermostat is
    stuck open. Ok I can fix that.... but what puzzles me is why the fan is
    running on?

    I will investigate the 1. Wiring harness, 2. the PCM/CCC/computer
    trouble codes (looks like I can do this on a 1995 model), and 3. engine
    coolant temp sensor.

    Everything else seems fine..... I hope it’s not the PCM.

    Symptom 2: Both reverse/back-up lights do not turn on when in reverse
    gear. Bulbs test fine. There is circuit continuity between Back-up Light
    fuse (at front engine fuse box) and lamps.

    My thoughts: From reading my Haynes manual.... I located the Back-up
    Light Switch on top of the manual transaxle. The Back-up Light fuse is
    good. With ignition key OFF, I unplugged the 2-wire connector from the
    switch, closed (short) the circuit on both terminals of the
    connector.... turned ON ignition key.... still no light, also ran
    engine.... still no light. I get no or a very small mV reading on both
    connector terminals (I am unhappy with getting a good ground connection
    though for my meter.... any suggestions with a good ground connection?).
    Wires and Wire-harness look in good shape. From the circuit diagram I
    should be reading Voltage on the battery side of the switch connector,
    then also on the ground side of the switch when in reverse if the switch
    is good. Right now it seems that I cannot conclude that the switch is bad.

    Thanks very much for your assistance, much appreciated.
    Cheers, Roger
    Roger E, Jul 3, 2008
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