Getting a PRNDL error

HUCK2009

MEMBER
2003 LINCOLN NAVIGATOR
220,000 MILES

I have gotten PRNDL errors before. And I have changed the relay and it cranks and works fine. I had to replace relay again a couple of months ago. Relay went bad yesterday and I replaced. This morning relay is no longer working again. I was able to swap out one of the original relays to get the truck to crank. Cranks with no problem. Why is that relay repeatedly blowing?

2 Replies

HUCK2009

MEMBER
2 POSTS

Clarification - when I said swap one of the original relays, I mean one of OEM relays from another slot on the fuse board.

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Tuesday, September 19th, 2017 AT 3:05 PM

CARADIODOC

MECHANIC
33,871 POSTS

Put in one of the relays you recently removed, and you will see it also solves the problem. Shift indicator errors are caused by the transmission range sensor, formerly known as the neutral safety switch. The older style used four to six individual switches in the assembly. Various combinations turned on for each gear selection. When any one of them had an intermittent connection and did not turn on at the appropriate time, it was seen as a non-existent switch pattern that could not be interpreted. The newer style is a variable resistor, similar in operation to a throttle position sensor. With a little dirt or bad connection on the movable contact, it can send a signal voltage that does not correspond to any of the gear selections. That will also cause a shift error. There should be a diagnostic fault code to confirm that.