Testing Solenoids And Relays - Bosch FIX 7677 Mode D'emploi

• If you hear tone - The switch is
closed.
• If you don't hear tone - The switch
is open.
8. Repeat Step 7 to verify switch op-
eration.
Good Switch: Tone turns ON and
OFF as you operate switch.
Bad Switch: Tone always ON or tone
always OFF as you operate switch.

Testing Solenoids and Relays

This test checks to see if a solenoid or
relay have a broken coil. If the coil tests
good, it is still possible that the relay or
solenoid are defective. The relay can
have contacts that are welded or worn
down, and the solenoid may stick when
the coil is energized. This test does not
check for those potential problems.
To test Solenoids and Relays (see Fig.
18):
Fig. 18
1. Insert BLACK test lead into COM
test lead jack.
2. I n s e r t R E D t e s t l e a d i n t o
3. Turn multimeter rotary switch to
200Ω function.
Most solenoids and relay coil resis-
tances are less than 200Ω. If meter
overranges, turn multimeter rotary
switch to next higher range. (see
Setting the Range on page 6)
Relay or
Solenoid
Red
Black
test lead jack.
4. Connect BLACK test lead to one
side of coil.
5. Connect RED test lead to other
side of coil.
6. View reading on display.
• Typical solenoid / relay coil resis-
tances are 200Ω or less.
• Refer to vehicle service manual for
your vehicles resistance range.
7. Test Results
Good Solenoid / Relay Coil: Display
in Step 6 is within manufacturers
specification.
Bad Solenoid / Relay Coil:
• Display in Step 6 is not within manu-
facturers specifications.
• Display reads overrange on every
ohms range indicating an open cir-
cuit.
NOTE: Some relays and solenoids
have a diode placed across the coil.
To test this diode see Testing Di-
odes on page 11.
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