Chapter 1, ST40 Speed Instrument
ST40 Instruments Service Manual 83149-2 2-3
E22037
Press the and keys together momentarily, to proceed to self-test stage 3.
Self-test stage 3
Note: A known good speed transducer must be connected for this test.
When entering self test stage 3, the instrument beeps and the display shows TEST3,
for 1 second.
A transducer test then starts. Manually spin the paddle wheel within 15 seconds of
starting this test.
If the instrument detects valid temperature and speed pulses within 15 seconds of the
start of test stage 3, PASS is shown on the display.
If the test fails, FAIL44 is displayed. Use the following table to try to isolate the cause.
Check Failure mode Action
Voltage at P11 Voltage approx. 11 V with Check TR10, R59 and associated
12 V battery supply components.
L10 Open circuit Replace L10.
L11 Open circuit Replace L11.
D4c Open circuit Replace D4.
Voltage at TEMP pin Outside range of 0.76 V to 1.00 V Check L14 for open circuit.
(at 18°C to 25°C) Check R60.
AVREF Outside range of 2.5 V ±0.25 V Check TR20, R61 & R62
Press the and keys together momentarily to exit self-test.
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