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Cruise control problem and gear indicator problem... Two birds, one stone?

sim303

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Jan 31, 2017
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Hi

In my quest to stamp out the few electrical gremlins in my truck (sadly I think it has had a hard life...)... I am faced with two apparently unrelated problems. Only now, I'm starting to wonder (hope against hope..?) whether they could be two manifestation of the same problem. I'd be interested to hear your thoughts:

Problem 1: Gear "D" indicator on dash flickers sometimes. Mostly it is on, but can flicker. It never fails completely though. Not fatal, just annoying. I've had the dash binacle off twice to swap bulb, clean its contacts, and to clean the contacts from the binacle itself to the loom.

Problem 2: Cruise control self-cancels after a relatively short time (almost always within a minute max). No DTC codes according to Techstream, and what information it gives doesn't suggest obvious fault.

Reading further into (1), I see talk of the so-called Park/Neutral switch on the transmission (in fact it detects every gear lever position, despite the name). These seem, in some cases at least, to be a cause of problems - particularly in the connector.

Could it be that this switch, or its connector, is not only making my D lamp flicker, but could be telling the CC system that "D" has been deselected (which is a "Cancel" condition)? The only evidence against this is that I did not particularly correlate the canceling of the CC with flickering of the "D" on the dash, but it's not that easy to tell.

Could this be a worthwhile avenue of attack?

sim
 
I believe you are onto something there, most likely.
 
Out of curiosity, what year and mileage is your 100 if the ‘D’ light still works?
 
175,000 miles...

But...

It's fixed! :D

I took the Neutral Safety Switch off (aka Park Neutral Switch etc). First oberservation - the connector was jammed with a dry white substance. Best guess is silicone grease, but old and dried out. I also opened the unit up, thoroughly cleaned, regreased and resealed it. I thoroughly cheaned the connectors, and refitted the unit. Then came re-aligning it - a tiny movement (the smallest you can reasonably make), makes an appreciable difference to how the lights sync with the gear stick position. The stick has a fair amount of play in it in each position so I took several attempts to try to the the given lamp to stay illuminated for all of that play, or as much as possible. It is a very sensitive setup. After about 4 or 5 goes, I got the lamps to work in each position, and to remain on when jiggling the stick in each position.

Took it for a 30 min drive - the D didn't flicker once, and the cruise control never self-cancelled unexpectedely! Previously it would never last more than 30 seconds.

So this was a massive win! Really looking forward to having the CC for my next big road trip this summer (Could have used it last year!)

sim
 
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