This is for our boy DougB who is out on a job in St. Louis and wont be able to get to a computer till this weekend.

Apparently getting lower gas mileage ~13mpg due to a faulty reed switch in the speedo which is somewhere in the gauge cluster (???) This was what he concluded from pulling a code.

Wondering what kind of time/difficulty/price/part# to get at this switch - Doug does not like the idea of losing the whole gauge for a junk yard find - doesnt want to lose his mileage ticks <img src="/forums/images/graemlins/baby.gif" alt="" /> <img src="/forums/images/graemlins/smile.gif" alt="" /> What can we say - he is a purist <img src="/forums/images/graemlins/lol.gif" alt="" />

Anyways I have no idea what this is about other than something about this reed switch being tied into the speedo gear AND ECU and its not telling the engine when its time to "coast" - didnt sound like an overdrive/tranny issue...our conversation was brief so I'm sorry if this isnt all that coherent, never heard of this and cant find anything about it on the Gen2 manual (though I havent looked extensively yet). If anyone has any ideas or input just put it here and he's much obliged <img src="/forums/images/graemlins/cheers.gif" alt="" />

95's may have a VSS senosr and not a reed switch. In the 91 Monty it is built into the Speedo and driven by the speedo cable. So if it did not change I noticed on mine lubing the speedo cable helped clear this fault. You can do this on a 91 just by remove the cluster cover. Speedo cable just clips on. Unclip and use your favorite lube, reinstall. Clear your fault codes(battery disconnect) and drive around to see if your fault reoccurs. After that on a 91 you would have to replace your speedo to replace your reed switch. <img src="/forums/images/graemlins/cheers.gif" alt="" />

Check Mouser or other electronics component sales companies for a reed switch that matches the broken one.

I can usually find replacement component level stuff for anything but an IC pretty easily.

Clay

First of all, my sincerest thanks to my buddy Phil for posting this! <img src="/forums/images/graemlins/cheers.gif" alt="" />

Secondly, I want to give props to the most valuable tool I own: my Victrionix pocket knife, which I use just about every day of the week. Being without proper tools, it was all I needed to completely remove and disassemble the speedo gauge... again in the parking lot of a hotel. <img src="/forums/images/graemlins/notooth.gif" alt="" />


Now for what I've discovered...

1) There's practically no way the reed switch will fail. For all intesive purposes, it is completely isolated from everything else anywhere (pic to follow). I now suspect that the code I got from the computer was stored in memory just after my rear end rebuild. I was so excited to finish up that project that I pulled out of the garage and zoomed over to a friends house forgetting to plug in the speedo cable. <img src="/forums/images/graemlins/rolleyes.gif" alt="" /> Quickly noticing that I was blazing a trail at 0mph, I pulled over at the next gas station and reconnected it. However, no spinning speedo cable = no reed swtich input. <img src="/forums/images/graemlins/drunk.gif" alt="" />

2) Contrary to my previous maintenance philosophy, lubing the speedo cable might not be the best thing in the world to do. I'd taken to dipping mine in ATF after every water crossing because I had a speedo cable die last year after not looking after it. However, ANY oily substance that finds its way onto the cable WILL MIGRATE UP INTO THE GAUGE CLUSTER. McV can tell you all about this! <img src="/forums/images/graemlins/smile.gif" alt="" />
Lube it and then wipe it clean!

3) Oil migrating up the speedo cable should not interfere with the reed switch. The way the speedo gauge is designed, any displaced oil will drip off before entering the internals of the speedo guage. Bill - no worries; false alarm! <img src="/forums/images/graemlins/cyclops.gif" alt="" />

4) Yesterday, my odometer locked up as did my trip ticker. I think this might have something to do with the electrnics parts cleaner I used to clean off parts of the speedo that had ATF on it. <img src="/forums/images/graemlins/frown.gif" alt="" /> HOWEVER, I noticed that the one that was the most stuck was the number "7" in 176,211. The point where the truck turned 170,000mi is about the same mileage where my speedo needle started bouncing. Coincidence??? Hmmm... <img src="/forums/images/graemlins/confused.gif" alt="" />

5) My poor fuel mileage may be accounted for by wind and a malfunctioning odometer. <img src="/forums/images/graemlins/angry.gif" alt="" />

6) I still have no idea what's making my speedo needle bounce, but it has become apparent that I will be needing a new speedo gauge.

7) I need a new speedo gauge!!! Anyone have a spare in good working order? I don't care about the mileage:D
(BTW, $200 new <img src="/forums/images/graemlins/scared.gif" alt="" />)


-DougB <img src="/forums/images/graemlins/cheers.gif" alt="" />


EDIT:
8) A malfunctioning reed switch should have little if any bearing on fuel mileage. I discovered this as I had to zoom around town last night without my main gauge cluster in place - the Raider will run fine without it, no problems. And that's why I call this truck the Millenium Falcon of automobiles. <img src="/forums/images/graemlins/smile.gif" alt="" />

I've got an extra speedo...

Thanks Bill, but I managed to pick up a handfull of gauges at the JY this morning for cheap. The Montero I skunked them off of had died at nearly exactly the same mileage I needed to reset mine! How cool is that?! <img src="/forums/images/graemlins/smile.gif" alt="" />

BTW, it appears that my bouncy speedo needle has something to do with the input on the speedo gauge. The problem is not the cable or anything south of that. I'll probably be making another post when I get everything sorted out and tested. Stay tuned! <img src="/forums/images/graemlins/wink.gif" alt="" />

If you ae replacing the speedo, you can reset the mileage to read what your original unit says. It's not too hard to do. Yes, to do so is against federal law, and I'm not suggesting that you lower the mileage of the vehicle, as that is the "intent" of the law, but to make the new unit read correctly should not raise any flags while licensing, transfering titles etc.
When I did my swap, I went to the V-6 guage cluster, to have the tach read correctly. I reset the speedo to 00000.0, and that is legal, as I have the original to back up the actual mileage.
Make sure you get a V-6 speedo, they are different then the 4-cylinder units.
Kary