Owner`s manual

84
Bulletins, Etc.
4
OHMsTests
Remove the GCU and unplug the wiring harness. See Figure
6 and 7.
The following two tests are for measuring the resistance of
the DLA circuit that send a signal to the GCU. If either test
fails the DLA is no good and should be replaced. If both
test are good the DLA is neither shorted or open, it is good.
An another component, connection or input is most likely at
fault.
Test 1: Identify the following wire ends in the plug.
Using a digital multi-meter set to the lowest scale (0-200
ohms) place the probes onto the harness making sure of a
good connection. Resistance should be between 47.7 and 58.3
ohms. See Figure 10.
If test 1 checks okay locate the following wire ends in the
plug, and check using test #2.
Test #1 Probe
Locations
Test #2 Probe
Locations
Figure 10. Test #1 Probe Locations for OHMs Test.
Figure 11. Test #2 Probe Locations for OHMs Test.
Old Style GCU
New Style GCU
Green LED
Light
Yellow LED
Light
Figure 12. Old Style GCU.
Figure 13. New Style GCU.
Blink Code Tests for the GCU
Speed control issues can also be diagnosis utilizing the on-
board - “Blink Code” diagnostic lights equipped in the new
style GCU. See Figure 13. The new GCUs do not store blink
code trouble codes, however speed control problems that are
experienced with a running engine can be quickly diagnosed
using the light codes and the blink code chart. See Figure 14.
Test 2: Identify the following wire ends in the plug.
Using a digital multi-meter set to the lowest scale (0-200
ohms) place the probes onto the harness making sure of a
good connection. Resistance should be between 47.7 and 58.3
ohms. See Figure 11.
If either test 1 or 2 fail the resistance test, the fault could also
be caused by a break/cut in the wiring harness. Inspect and
test for a potential harness issue prior to replacing the DLA
assembly.