'97 ESOF issue

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Oct 13, 2009 | 03:24 AM

collmanb

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'97 ESOF issue

I have a problem with my ESOF that is a bit different than any I have found here. I parked my truck for a month after driving it down the highway. When I went to start it up, I noticed that 4hi was engaged though the rotary switch was in the 2hi position.At a certain point (after clearing the check engine light for a dirty MAF sensor) it started working normally. Next time I use the truck same problem returns. However, when I tear open the dash and disconnect the switch it goes into 2hi. In fact I was able to jump it with resistors and get it to switch normally. So I figured the switch was bad, but no, 3.89k ohms for 2hi, 1.1k for 4hi and 360 for 4lo when I test it with the multimeter. What would cause this? (Incidentally it will switch into 4lo in the 4hi position if the truck is in neutral, etc.)

I guess one more thing to mention, when I jumped it with the stated resistance values yesterday and it worked normally, I was just jumping across the middle (dark blue) wires and the others were not connected to anything when the switch was out - maybe that has something to do with it.

Does that make sense to anyone?

Thanks,
Ben

Oct 13, 2009 | 11:52 PM

collmanb

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esof guess

I looked again at sscully's page o' wiring diagrams. I see that the control circuit is isolated from the other two wires in the switch, so that's out (presumably). I see, though, that the control wires are tied into the multi-function switch. The MF-MFS misbehaved once before due to corrosion which I removed with an eraser several years ago thanks to helpful forum posts here or elsewhere. Maybe it's time to clean it up again. I will post if that helps or not. It definitely seems like an electrical problem, so...