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Breakout box overlays needed

Bruce Rock

Well-Known Member
December 31, 2001
Reaction score
City, State
Kaukauna, Wisconsin
Year, Model & Trim Level
'94 XLT
My '94 has developed a surge at cruise (about 60 mph) when running closed loop. No check engine light, so I'm assuming no DTC have been set. During open loop operation (by disconnecting the TPS or at wide open throttle) It seems to run smoother.

I'm thinking one or both of the O2 sensors might be bad. But since they are a little hard to change and expensive I'd like to trouble shoot further.

I've got a breakout box but don't have an overlay for the 4.0 engine. From a previous post I know the O2 sensor posts might be 43 and 46 & 44 and 46. Could someone confirm that and, if possible, take a picture of the overlay for the 4.0 and the 3.8 (I also have a '95 Sable).

The factory CD's I have for both vehicles say a breakout box is a required tool for trouble shooting, but doesn't reference the breakout box pins to what sensors they connect to, or what voltages to expect.