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Missing some ooomphhhh!

rickybobby

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City, State
Battle Creek, mi
Year, Model & Trim Level
'97 XLT
Definitely all connectors are snugly in their sockets. I am starting to think of refurbishing the rear axle differential. Am I barking up the wrong tree? Should I try with another sensor? Are these known to go duff? How can I test them?

you are definatly barking up the wrong tree. Your code is for a transmission sensor. There is an output speed sensor in the transmission, sometimes it is referred to as an overdrive drum sensor. I will try to get a pic of it from mine tomorrow
 


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Lechuga

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City, State
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Year, Model & Trim Level
'98 XLT
its possible the egr is staying open during full throttle or open too much during cruise speeds. you can try blocking the egr and taking it for test run to see if it improves.

Cancelled out the EGR with a metal plate but there was no improvement at cruise speeds :(
 




Lechuga

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'98 XLT
you are definatly barking up the wrong tree. Your code is for a transmission sensor. There is an output speed sensor in the transmission, sometimes it is referred to as an overdrive drum sensor. I will try to get a pic of it from mine tomorrow

I don't have an OSS in the transmission. There is no hole either. Seen the pictures in other posts and looked for it. Nothing. I read it was removed in '98 models and later and moved back to the rear diff.

I've now tried with two new sensors on the rear diff and still no signal. I've also discovered that the key doesn't open the doors (I always used the remote until now) and I am starting to think the previous owner might have replaced the ECM for a different unit from a prior year found in a scrapyard. That would explain why it's not reading anything from the sensor, and might also explain the poor performance. Any comments?
 




christopherjones

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prince george, british columbia
Year, Model & Trim Level
96 xl
It's funny you mention that 98 s don't have it as my 98 does "02/98". Anyways it is just near where the trans vent line comes out at the back on the drivers side, and has a tiny connector there and tiny bolt. I was disappointed to see this on mine as I was hoping to use my 96 case and do a vb swap, looks like its job weld time
 




Lechuga

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'98 XLT
It's funny you mention that 98 s don't have it as my 98 does "02/98". Anyways it is just near where the trans vent line comes out at the back on the drivers side, and has a tiny connector there and tiny bolt. I was disappointed to see this on mine as I was hoping to use my 96 case and do a vb swap, looks like its job weld time

Mine definitely doesn't have it. It's a "09/98"
 




christopherjones

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prince george, british columbia
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96 xl
Did you at one point change the ECM? To an early 98 maybe was the transmission replaced in the truck before? If so maybe they put the wrong year transmission in and just ignored the error
 




Lechuga

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'98 XLT
Did you at one point change the ECM? To an early 98 maybe was the transmission replaced in the truck before? If so maybe they put the wrong year transmission in and just ignored the error

Well it could be. I think the centre diff is from a 97 and discovering that the key won't open the doors leads me to believe someone swapped the ECM sometime in the past, but couldn't be bothered with the door locks. Probably got it from a scrapyard.
 




Lechuga

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I've arranged to meet a mechanic with ECM programming equipment on Wednesday. I guess I'll know more after that :)
 




Lechuga

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The ECM in the engine bay is covered/protected by a sort of housing around it. How is it removed? It doesn't seem to have any nuts or bolts to hold it in place. TIA
Chris
 




christopherjones

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prince george, british columbia
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96 xl
There's a bolt in the center of the harness you loosen off and work the connector out. Then there should be a black ISh rubber boot around the ECM with a bolt on either side take that off and the ECM should just slide rot out
 




Lechuga

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There's a bolt in the center of the harness you loosen off and work the connector out. Then there should be a black ISh rubber boot around the ECM with a bolt on either side take that off and the ECM should just slide rot out

Thanks Chris. But I mean a black steel shroud that covers the center bolt, connector and rubber boot. I'm stumped. I'll take a photo and upload it later.
 




Lechuga

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Removed it by drilling out two rivets. The ECM looks OK. I mean nothing is burnt. So I am now looking at the wiring (again).

Does anyone have a wiring diagram for this rear diff sensor? I saw two wires coming out and going along the fuel tank to just under the passenger seat and then disappearing into the body. Where do they go? What do they connect to? I'm looking, looking, looking
 




Lechuga

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'98 XLT
Please feel free to jump in at any time and correct me if I'm wrong. I've read elsewhere the rear diff sensor wires run to ABS (in the engine bay) and from there signal the ECM (via pin #57). So I am looking for an ABS wiring diagram
 




bobflood

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Powder Springs, GA
Year, Model & Trim Level
1997 Eddie Bauer V8 2WD
Removed it by drilling out two rivets. The ECM looks OK. I mean nothing is burnt. So I am now looking at the wiring (again).

Does anyone have a wiring diagram for this rear diff sensor? I saw two wires coming out and going along the fuel tank to just under the passenger seat and then disappearing into the body. Where do they go? What do they connect to? I'm looking, looking, looking

Great source for wiring information:
Auto - Online Repair Info
http://search.ebscohost.com/
ID: rrcc
PW: rebsco
Select: Auto Repair Reference Center
Fill in: Find Your Vehicle
Follow prompts down to Wiring Diagrams.
Won't provide physical wire routing, but will identify wire colors, terminal numbers, etc.
 




christopherjones

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96 xl




christopherjones

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prince george, british columbia
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96 xl
If the code is OSS then it wouldn't be the tabs sensor on your diff, that is called vss OSS is definately a transmission sensor now your ECM box may not be fried or anything but check the date code on it. If it was ever replaced it could be from an early 98 that used the OSS on the trans . The sensor would go in just ahead of the mating flange of your extension housing/ tail housing (if your 2wd) it's very small and doesn't stick out like some harnesses it lays flat , it could also be a corroded harness somewhere. Places with a high salt content in the moisture or that use salt to de ice roads get that crap in all the connectors,and it stops the contacts from connecting properly
 




Lechuga

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Year, Model & Trim Level
'98 XLT
Thanks bobflood! I followed your link and found the wiring diagrams. It would seem the VSS output signal to the ECM is #10. Valuable!

chrisjones: My Ex is a 4x4. I'm starting to believe the problem is in the wiring. I'll take some time this weekend to check it with my multitester. Now that I know where the wires go...

I took a photo of the ECM (for reference) and it's an ML2-463, which I've read is the right one for my type of car.

The error code I've got is: P0720. Now, I have no idea if its OSS or VSS... All I know is I definitively do NOT have an OSS sensor in the transmission.

I really want to get to the bottom of this. And I still think I'm missing some ooomph! For a 207bhp car, it feels more like 100 :(
 




Snuke

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Wichita, KS
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1999 Sport
Guys, correct me if I am wrong, but doesn't his issue sound like that sticky we have around here pertaining to the throttle wire slipping and only opening the throttle body 25 to 30% at what should be wide open throttle? Mine is doing the same thing, only I have a manual transmission, but the engine felt INCREDIBLY under-powered until I did that zip-tie trick in the sticky. Anyone have the link for him? I am lazy....
 




Lechuga

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'98 XLT
Snuke, my scanner tells me that what should be WOT is actually 94%. No so bad. I'm still working to figure out the P0720 DTC, but I'll check out the zip-tie trick after that ;)
 


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Lechuga

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It's funny you mention that 98 s don't have it as my 98 does "02/98". Anyways it is just near where the trans vent line comes out at the back on the drivers side, and has a tiny connector there and tiny bolt. I was disappointed to see this on mine as I was hoping to use my 96 case and do a vb swap, looks like its job weld time

Your post has me thinking. Although I definitively do not have a sensor on the trans, there is a sensor (broken) in the rear of the TC near the rear drive shaft, which I was told was unused in my Explorer. Maybe this is the origin of my problem. Is there a way to tell what specs an Ex has when it left the factory by its VIN? I mean in addition to the basic info provided by the VIN decoder...
 




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