Speedo and Trans weird problems

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Nov 3, 2003 | 10:09 PM

paulcalif

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Speedo and Trans weird problems

Having weird problems with my 98 Expedition. The speedometer doesn't read and then it goes real high. The transmission is shifting weird. I'm pretty sure the transmission is looking for a signal from a speed sensor that it's not getting reliably. The check engine light has come on and the error is speed sensor, "P500 vehicle speed sensor "A"

I know what you're thinking, it's the speed sensor, but I changed it. At least I changed one of them. I changed the one in the differential. That didn't make any difference. I supposed I could have gotten a bad one. Wouldn't be the first time. But the last time I bought a bad electrical part was for my 3 year old 66 VW, so it's been awhile.

The parts guy tells me there is another speed sensor on the transmission but he has never sold one. I didn't think to ask him how long he has worked there.

Anybody have any ideas???

Would sure appreciate you help.

Nov 4, 2003 | 01:10 AM

paulcalif

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I should have mentioned that this is a 4 wheel drive

Nov 4, 2003 | 02:00 AM

BigMattXXL

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From: Annapolis, Maryland

Looks like the speed sensor he sold you was the ABS Speed Sensor - about $20, goes in the rear differential. Totally unrelated part.

The vehicle speed sensor I think you're looking for is in the transfer case, towards the rear, on top, and probably costs a lot more.

Let me know what you find.

XXL

Nov 4, 2003 | 08:58 AM

paulcalif

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Great, checking into that now. Called the dealer, the service advisor was clueless. Thanks for the reply

Nov 4, 2003 | 03:32 PM

paulcalif

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This gets stranger by the minute. I have the Vehicle Speed Sensor in my hand. This has a gear on the end of it, and the gear is stripped. The Ford dealer says the sensor comes without the gear, and they are having a very hard time finding the gear. Any ideas, anyone?

I'm wondering why the gear is stipped (it's actually missing parts of the teeth on the end)

Has anyone else pulled theirs? I've learned they are color coded and are identified by the number of teeth. Mine has 21 teeth and is dark purple. I ask because I'm wondering if anyone else has the same gear. It looks like the transmission has had work done to it, and I suppose it's possible that they put the wrong gear back in. That would explain the ground teeth. Another possible explanation might be the clip that holds the gear onto the sensor. It sticks out a hair and has a shiney spot at it's highest point. Might that be binding?

Stay tuned.

Last edited by paulcalif; Nov 4, 2003 at 03:40 PM.

Nov 4, 2003 | 11:10 PM

MisterCMK

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From: Blue Hill Township

You might be able to find a new sensor at a junk yard. Maybe... Otherwise, check some of the ford racing catalogs to see if they might have one that fits. The color coding is used to tell how it will make the speedometer read. I once saw a table for pontiac ones that had to put in your axel ration, tranny drive gear, tire size I think, and it told you what color you needed to get the speedo to read accurately.

Nov 5, 2003 | 12:58 AM

paulcalif

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Your reply about the color is interesting. Went to a speedo shop today, they were supposed to have one or know where to get one, but they didn't. Wasted most of the day looking for one. Finally a local ford dealer said they could get it by tomorrow, both the sensor and the gear. (I'll believe it when I see it).

In the mean time, I used a mirror and flashlight to look into the hole where the sensor goes. The gear inside the transmission that meshes with the one on the sensor is also plastic (cheap). It looks ok, but it's hard to tell for sure. There were also some abrasions on the inside of the hole, I hope that's not a bad sign.