Volvo VNL Service Manual page 58

Group 38 Instrumentation, VNL, VNM
4 Turn the ignition ON and use a voltmeter to mea-
sure the voltage between pins 2 and 4 on the RX
connector. Measurements should be as follows:
Table B: Voltage Check
Fuel Level
Empty tank
1/4 tank
1/2 tank
3/4 tank
Full tank
•
If voltage is as shown in Table B, connect the
connector and check the fuel gauge socket for
the same value at the connector. If the value is
the same replace the fuel level gauge. If the
voltage is not at the socket replace the right cir-
cuit board.
•
If voltage is not as shown in Table B, go to step
5.
5 Check voltage between RX-2 and LX-3.
•
If voltage is as shown in the Table B, check the
circuit, connector terminals and wiring from
RX–4 to LX–3, and replace components such
as terminals or wiring as necessary.
•
If voltage is not as shown in Table B, check for
12V on pin LX–10, and for ground on LX-12; if
voltage and ground are not present, check
wiring and fuses. If ok, check the input to LX-2.
It must be within the correct range per Table A;
if not, check the sender. Then check for voltage
output from LX-3. If it is not present, replace the
left circuit board.
6 If the pointer constantly stays on the 1/2 mark,
full mark, or falls below the empty mark, the
most likely cause is a wiring problem.
56
Expected Reading
(RX-2 to RX-4
and RX-2 to LX-3)
0.19 volts ±10%
1.1 volts ±10%
2.3 volts ±10%
3.5 volts ±10%
4.7 volts ±10%
a. If the pointer stays below "E" AND the
pointer moves slightly during the gauge test,
there is no signal on the ground input. Check
for an open circuit on RX-2.
Note that RX-2 is associated with the axle tem-
perature circuit, so that gauge may be affected
also.
W3002496
Fig. 67:
b. If the pointer stays above "F" AND does
not move during the cluster self test, there is
no signal on the +5V input to the cluster. Check
LY-15 and RX-12 for an open circuit.
W3002494
Fig. 68:
c. If the pointer stays at the 1/2 mark AND
the pointer does not move during the cluster
self test, there is no signal on the fuel level in-
put. Check RX-4 for an open circuit.
W3002495
Fig. 69:
Troubleshooting