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VSS necessary with 4R70W?

Broncos n' VWs

Sr. Member
Joined
Nov 6, 2005
Messages
360
Is it necessary to use a VSS (EFI engine) with a 4R70W? I will be using a Baumannator TCS integrated with the RJM EFI harness. I had a VSS dropped off to me at work from a local parts house and the VSS has a white "plug" where the speedo cable goes. Is that just a cover I can pull out or did I get the wrong VSS? Or can I just run w/o a VSS all together? Any help or advice is appreciated,
 

Socal Tom

Bronco Guru
Joined
Feb 12, 2004
Messages
2,442
Loc.
San Diego, CA
The 4r70W has a TSS ( transmission speed sensor) that the Baumanator TCS will use for its inputs. Its basically a VSS built in to the trans, so you don't need another one on the transfer case.
Tom
 

Broncobowsher

Total hack
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Jun 4, 2002
Messages
34,821
The Baumanator uses the OSS (Output Shaft Speed) sensor to make all it's shift programming. Later Explorers pulled vehicle speed off the ABS system and no longer neeed the VSS on the transmission. The plug was the cheap fix without having to re-engineer the tailhousing.

So the VSS is not needed for the transmission, but the EFI (mustang style I presume) generally does like the VSS. So if you use the VSS it is for the engine's benifit, not the transmission.

I am guessing you have a 2WD transmission?
 

Ryan

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Aug 29, 2003
Messages
739
Loc.
Lansing, MI
The OSS (Output Shaft Speed) is in the drivers side of the 4R70W
The VSS (Vehicle Speed Sensor) will go in the transfer case.

I think the Baumanator needs the sensor in the transfer case, so it will shift correctly in Low range.

all 5.0L 4R70W Explorers used both sensors from 1996-2001
VSS at pin 58 and the OSS at pin 84
 
OP
OP
Broncos n' VWs

Broncos n' VWs

Sr. Member
Joined
Nov 6, 2005
Messages
360
I am guessing you have a 2WD transmission?

I actually have the 4WD version. The VSS is from a 1990 Mustang. I ordered it today from the local parts shop and it was delivered this afternoon. If I choose to run the VSS in the t-case, do I just need to pull the plastic plug inside the VSS or do I need to return it and get one that does not have the plug installed?
 

Nobody

Bronco Guru
Joined
Feb 15, 2005
Messages
1,215
Loc.
Stanwood
Yes that white plastic plug can be removed. If you intend to use your stock speedo cable, you will have to drill out the vss.
 

Broncobowsher

Total hack
Joined
Jun 4, 2002
Messages
34,821
The OSS (Output Shaft Speed) is in the drivers side of the 4R70W
The VSS (Vehicle Speed Sensor) will go in the transfer case.

I think the Baumanator needs the sensor in the transfer case, so it will shift correctly in Low range.

all 5.0L 4R70W Explorers used both sensors from 1996-2001
VSS at pin 58 and the OSS at pin 84

The baumanator only needs the VSS if you have an E4OD (no OSS)
The 4R70W only needs the OSS
 

kholding

Bronco Guru
Joined
Sep 6, 2010
Messages
2,209
Loc.
Las Vegas, NV
So if I have the RJM harness and Baumanator for my 4r70w, do I need to use both VSS and OSS? If I don't need the VSS, will that cause any issues with the harness? Thanks.
 

rjrobin2002

Contributor
Bronco Guru
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Oct 13, 2007
Messages
2,643
I had a rjm harness and Bauman optishift in my Bronco I just sold. I did not install the VSS, runs great.
 

Rox Crusher

Bronco Guru
Joined
Dec 13, 2008
Messages
2,772
same here, although I haven't tested whether it shifts correctly with the transfer case in low range

not to worry, I will test the hell out of it next week in Moab !
 

Broncobowsher

Total hack
Joined
Jun 4, 2002
Messages
34,821
OSS deals with transmission shifting.
VSS deals with coasting engine stall and sometimes high speed (100 MPH+) ignition timing.
 
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