87 150 cruise control surging
03-26-2019, 03:59 PM
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87 150 cruise control surging
'87 F150, 302ci, 1/2 ton 2wd, XLT Lariat. After 2 years I finally replaced the turn signal switch. Everything is working well except for the cruise control. The battery has been disconnected several times over the last 2 years. I have a fleet truck for work so my F150 sits way too much. The problem is I have engaged the Cruise Control and it surges. I have driven it about 10 miles. The CC engages, accelerates and goes into coast as designed. The switches are good from the testing. When I stretched it out for a couple of miles the RPM would aggressively accelerate to plus 8 mph then coast to the set speed limit, then repeat. This was not the case prior to the turn signal switch going South.
Is there a run in time for the CC electronics? Do I need to run it in so to speak? Are there specific items that cause this surging issue that I need to investigate? I know there are several pieces and parts that make this work. The manual was not much help at all.
Is there a run in time for the CC electronics? Do I need to run it in so to speak? Are there specific items that cause this surging issue that I need to investigate? I know there are several pieces and parts that make this work. The manual was not much help at all.
03-26-2019, 11:35 PM
#3
I have a 92 300 i6 with the same issue. Mine surges about 4-5 mph though. I have scoped the vss signal to the cruise controller, swapped cruise controllers with both V8 and 6 cyl units and swapped the vacuum modulator cable pull assembly...I even adjusted the potentiometer internal to them- everything checks correct...I basically gave up on it. they went to an electric cable pull cruise in 94 with integrated electronics- there must have been issues with it, i just can't find anybody who knows what the typical malfunction cause is.
03-27-2019, 02:26 AM
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Other than the sliding contacts for the horn/cruise buttons, the turn/hazard switch has nothing to do with the cruise. The only possible interaction would be that the new contacts don't touch the steering wheel rings in the same way. But that alone can't cause surging. I'd check the cruise servo for dirt-dauber wasp contamination of the vent ports.