Cruise control install, works, then doesnt

97 4.0 (4.6:thumbup AX15 came without cruise, grabbed a junkyard set and it worked perfectly. Later in the day it stopped working and the dash light wont come on. I think I have a vac problem as I only have defrost, but the cruise did work for a couple different trips. I havent checked the vac lines yet, but would they be responsible for the light not even coming on? Next Ill try the steering wheel switch, then the harness on my vehicle that sat open for 13 years.

Maybe a connector wasn't seated properly and shook loose?

Grab a DMM and verify your ground. 0.5 ohm is desireable.

If you only have defrost - that is a vacuum leak. Fix the vacuum leak and it should restore your cruise control.

the_weirdo said:

If you only have defrost - that is a vacuum leak. Fix the vacuum leak and it should restore your cruise control.

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I knew vac controls both, but would the vac leak be responsible for the light not coming on or just poor performance of the system?

You have a known problem that is adversely effecting two systems.

Fix the known problem first.