Diagnosing the Engine Temperature Gauge

Tag: diagnostics gauges engine

SPECIFIC TEST PROCEDURE FOR TEMPERATURE GAUGE USED BY CATALINA YACHTS

(Other systems may use a different procedure.)

There are FOUR major sources of temp gauge problems.  Read on for the testing procedure.

 

 

 

1 - The temp GAUGE in the engine control panel may be defective.

TEST PROCEDURE :

• Disconnect BROWN sender wire from "S" terminal on gauge.
• Turn on ignition switch.
• Pointer must deflect to extreme left By temporarily shorting together the "S" (sender) and the "G" (ground) studs, pointer must deflect to the extreme right.
• Re-connect the BROWN sender wire to the gauge after the test.

2 - The brown SENDER WIRE may be DISCONNECTED from the sending unit at the engine or SHORTED TO GROUND.

TEST PROCEDURE:

• Disconnect brown SENDER WIRE from terminal at sending unit on engine.
• Attach brown wire to a KNOWN GROUND, such as engine block or battery NEGATIVE.
• DO NOT ASSUME THE BODY OF SENDER IS GROUNDED.
• Turn on ignition switch.
• Pointer must deflect to extreme right, as in previous test.Disconnect brown wire from ground.
• If pointer STILL deflects to extreme right, brown wire is GROUNDED at some point between the sender and gauge.
• Check ALL connection points on brown wire or replace the entire wire.

3 - The SENDING UNIT may not be properly grounded to the engine block.

TEST PROCEDURE:

• If the gauge tests "GOOD" and BROWN wire tests "GOOD", touch BROWN wire to the BODY OF THE SENDER.(the flat area where you would place the wrench to install the sender.)
• Make sure this area is free of paint. If pointer does not deflect to right, (as in test above), the sender body is NOT GROUNDED.
• Remove the sender, and inspect the threads. If necessary, remove any TEFLON TAPE or PIPE DOPE COMPOUND.
• Clean the threads, apply some coolant to the threads, and reinstall the sender in the engine.

4 - The SENDING UNIT in the engine may be defective or the wrong unit may have been installed.

TEST PROCEDURE:

• If the gauge tests "GOOD", the BROWN wire test "GOOD", and the SENDER GROUND tests "GOOD" the sending unit in the engine is defective
• or the "WRONG" unit may have been installed. The CORRECT" sending unit has a specification of:

STEWART WARNER, 240 TO 33 OHMS RESISTANCE

There are several other resistance specifications available but those sending units WILL NOT WORK in this application.

 

TEST PROCEDURE, W/TEMP GAUGE PANEL DEPARTMENT April 22, 2003

* WHITTIER, CA. 90601 * * SEAWARD PRODUCTS *

Fuel Gage -

(562)699-7997 (562)699-0908 FAX

Jamie Pett

Bella Luna

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