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97 k1500 temp gauge.

This is a discussion on 97 k1500 temp gauge. within the Technical / Maintenance forums, part of the General Discussion category; I recently bought a truck and im having problems with the temp gauge. when i got the truck the gauge ...

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    97 k1500 temp gauge.


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    I recently bought a truck and im having problems with the temp gauge. when i got the truck the gauge would read about 170 degrees. i replaced the sending unit sensor and now the gauge reads about 240 degrees. the gauge fluctuates a little while driving also. i bought a IR gun and from what i can tell the engine is running 195 degrees if i point the gun directly at the sending unit sensor. i put an ohm meter on the sensor and it read 4.2 when it was cold and .4 when it was hot. how can i go about testing all of these things to try and figure out my problem? thanks in advance for your help.

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    Registered Nerd 88montess's Avatar
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    Re: 97 k1500 temp gauge.

    I found the actual ohm readings last night when I was looking for something else, I'll post them when I get home, but it sounds like you may have gotten the wrong sending unit. Also, the gauges in these trucks are not known for being extremely accurate, it seems to be pretty common for them to read 160-170 when the motor is fully warmed up.
    78 Camaro - ?03k||88 MCSS - tired 305|built 2004R|G80 GT4|197k||92 Camaro RS - LT1|700R4|2.73|139k
    88 K2500 Scottsdale RCLB - knocking L05|HM290|G80 GT4|posi-lok|300k+
    97 K3500 Silverado RCLB - L29|4L80E|0411|LS6 injectors|G80 GT5|220k & counting

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    I checked the part # on the new sending unit and it show its the right on but it could be faulty. I'm gonna flush the system and cleanup and try the old sensor. I am curious about those readings though.

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    Registered Nerd 88montess's Avatar
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    Re: 97 k1500 temp gauge.

    Well the one that actually specified it was a different year, but I think based on the troubleshooting steps I have we can make a semi educated guess that cold is 1305 ohms & hot is 49.5 ohms.

    COOLANT TEMPERATURE GAUGE (GASOLINE)

    Gauge Indicates Hot All The Time Or CHECK GAGES Light Is On
    With Coolant Temperature Below Normal


    Disconnect engine coolant temperature sender connector. Turn
    ignition on. If temperature gauge indicates cold (100F or less for
    gas, 160F or less for diesel), replace engine coolant temperature
    sender. If temperature gauge does not indicate cold, locate and repair
    short to ground in Dark Green wire between engine coolant temperature
    sender connector and instrument cluster connector. If wire is okay,
    replace instrument cluster.

    Gauge Indicates Cold All The Time

    1) Disconnect engine coolant temperature sender connector.
    Connect fused jumper wire between engine coolant temperature sender
    connector terminal "A" (Dark Green wire) and ground. Turn ignition on.
    If temperature gauge indicates hot, replace sending unit.
    2) If temperature gauge does not indicate hot, locate and
    repair open in Dark Green wire between engine coolant temperature
    sender connector and instrument cluster connector. If wire is okay,
    replace instrument cluster.

    Gauge Inaccurate

    1) Disconnect engine coolant temperature sender connector.
    Connect Red wire from Gauge Tester (J-33431-B) to Dark Green wire.
    Connect other Red wire to ground. Adjust resistance dials to 1305
    ohms, then to 49.5 ohms.
    2) If temperature gauge indicates cold, then hot, replace
    engine coolant temperature sender. If gauge is still not correct,
    replace instrument cluster.
    78 Camaro - ?03k||88 MCSS - tired 305|built 2004R|G80 GT4|197k||92 Camaro RS - LT1|700R4|2.73|139k
    88 K2500 Scottsdale RCLB - knocking L05|HM290|G80 GT4|posi-lok|300k+
    97 K3500 Silverado RCLB - L29|4L80E|0411|LS6 injectors|G80 GT5|220k & counting

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    Today I jumped the sender wire and it showed the temp gauge pegged to the right. I got another sender unit sensor and water temp sensor. I'm going to install those tomorrow and see what happens. I guess if that doesn't work then it must be the gauge cluster? I'm running out of options and money. I just spent a ton of money on the spider upgrade and every gasket imaginable. Ill be installing all that this weekend.

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    So I changed both sensors this morning and the gauge seems to be reading where it's supposed to. If it is working correctly then it looks like I might have a sticky thermostat. Does stop leak usually mess thermostats up? I flushed all that crap out.

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    Registered Nerd 88montess's Avatar
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    Re: 97 k1500 temp gauge.

    stop leak can cause all sorts of havoc with a cooling system so it's hard to say if it's the cause or not.

    Best way to find out if it's not opening is to let the truck warm up & when it's almost to operating temperature start monitoring the block & radiator temperature with your IR thermometer. It should (assuming no one has changed the thermostat to a different temp) start sending coolant to the radiator around 190-200. Another way is if you have a smartphone there are bluetooth OBDII dongles available that can connect to an app on your phone, that'll let you see what the pcm sees, including what its temp sender is indicating, that might be easier since you can drive normally & have someone else watch the live data & see how it correlates to your temp gauge in the dash.
    78 Camaro - ?03k||88 MCSS - tired 305|built 2004R|G80 GT4|197k||92 Camaro RS - LT1|700R4|2.73|139k
    88 K2500 Scottsdale RCLB - knocking L05|HM290|G80 GT4|posi-lok|300k+
    97 K3500 Silverado RCLB - L29|4L80E|0411|LS6 injectors|G80 GT5|220k & counting

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    Habitual Troublemaker cancritter's Avatar
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    Re: 97 k1500 temp gauge.

    lve bought bad "new" thermosts before so dont rule it out
    [Stole/FOUND 13/03/08 :O)
    91GM 4x4 excb 5.7 @ 40 over, Westers,Eld 3704.Lunati Trickflow 195 @1.6 RR,Walpro 190/overbuilt 700r4 /TCS TC,4.10/tru trac,14 blt,Hooker LT,areofilter,Extreme TBI.MSD.AGR still adding
    07/ 6.7 Cummins..truck included
    70 fury 3
    71 sport fury GT

 

 

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