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Iowa GMC
08-18-2007, 04:24 PM
I have a 88 Suburban 3/4 ton 4x4 with a 5.7 liter TBI.

I should have a th400 tranny correct the pan sure looks like th400 to me.

I have never had a TBI truck before I am going to assume that the transmission is stand alone in my case.

The ECU for TBI only controls fuel and spark correct?
performabuilt2
08-18-2007, 08:37 PM
no the TH400 is a hydraulic controlled tranny no electronics there
Iowa GMC
08-23-2007, 08:48 AM
Thank for the info.

I was pretty sure but it's nice to have a second opinion.
Fast305
08-23-2007, 10:01 AM
no the TH400 is a hydraulic controlled tranny no electronics there

The Kickdown on the TH400 is controlled by the ECM through a relay though.
Iowa GMC
08-24-2007, 08:18 AM
Can this be converted to cable controlled setup?
Fast305
08-24-2007, 08:49 AM
Can this be converted to cable controlled setup?

NO, but you can put a carb or accelerator mounted downshift switch on it and wire it to the transmission's passing gear terminal.
Iowa GMC
08-29-2007, 12:33 PM
Ok that sound easy enough thanks for the information.