Brake light bulbs and OD / Cruse....

[David Emmerich]

Greetings all...I have a tech note concerning the Over Drive and Cruse Control on a 1994 Ranger with a 4.0 and Auto trans...I am an Electrical Engineer, and this one stumped me for 3 weeks. Every thing was working fine on my $350.00 Wonder truck...1994, had 94,000 miles, and belonged to a 94 yr old farmer who side swiped a pole and battered the right side badly...anyway, I had to put in new tail lights on the left side, so I put new LED units in as replacements. Then to make it look a bit more uniform, I changed the bulbs on the right side to LED ones too. So far, so good. About a month later, the OD and Cruse stopped working when I was about 400 miles from home. I poked around a while, checking fuses and connector and grounds, all to no help. I made it home alright, got better MPG in fact...and started to trouble shot the problem...no codes showed up on a scan, all the voltages were good, etc.

One morning a coworker mentioned that my right brake light wasn't working, so at lunch I took out the LED bulb and put in a regular bulb. On my way home I found that everything was working again!!!!

I checked the voltage on the Brake light wire, and found that with the BL sw not made, I had 0 volts with a regular bulb, but 5.5 volts with a LED bulb in the socket. Now the ECM monitors the brake light wire to enable canceling Cruse when you hit the brake, and the 5.5 volts was high enough to make it think that the brake peddle was being pushed, all the time. Now that I have the correct bulb back in the right side stop light, all has been good for the past 50,000 miles.

Safe truckin....
David

 

[alwaysFlOoReD]

Good to know. Thanks

 

[modelageek]

great info......thanks.......

 

[trail B2]

Thank you we need more solved problems on here.

 

[modelageek]

Thank you we need more solved problems on here.

I agree. I have tried a few ways to get people to post conclusions on their threads. I am starting to help out less. whenever I post suggestions about how a poster can get better results I get some Idiot telling me I am rude or inconsiderate. then the thread becomes useless with bickering. I have started to look the original poster up and if they have other threads I go and see if they concluded them. if they didn't conclude them I am leery of helping . They just wan to hit and run and not contribute. sounds like i am whining but the world is a 2 way street.