jdustin

I just did a ls swap 5.3 4l60e 4x4 on a 99 suburban. It wont shift out of first gear. I switched vss siganl wires to the 5.3 pcm and still doesnt shift

mrvedit

Does the speedometer work? Does a scanner show speed?
Are you sure the shift linkage works and you are not in D1?
Sorry if these are too obvious, but those are the most obvious.

jdustin

The truck is at the exhaust shop. I need to wire in a data link connector so I can put a scantool on it. I am using the old harness for the transfercase and switched the vss wires to the new pcm. I know other people have done this I jus gotta figure out why mine doesnt work. I have power at the transmission and no the speedometer doesnt work but I think I may have hooked it up wrong, but That may allso be because of a vss problem.

mrvedit

I would put 100% effort into getting the speedometer to work. I suspect the trans will shift then too.

jdustin

will the speedo affect the shifting? or is the vss affecting the speedo? ..lol.. thats the question I suppose??

mrvedit

The VSS connects to the PCM and the PCM runs the speedometer. The PCM controls the shifting and will not shift until certain speeds are reached. Hence you are stuck in 1st gear.

jdustin

I understand that. Let me give you a brief run down of how this is hooked up. The 99 suburban and late 90's model gm trucks the wiring harness runs through the cab and does not unplug in the engine bay comlpletely letting you take it outwith the engine. I saw several people on the internet doing this swap and leaving the old pcm in place saying it was the simplest way to do it. So thats what I did. My old harness is running my starter and neutral safety switch and my transfercase since the 4x4 switch and controls is in the truck. My vss sensor is on the transfercase and I switched the vss wires from the old pcm to the new and the tcc wire and speedo. The vss wires dont go strait the pcm I am thinking on 4x4 I see on the wiring diagram. I
t looks like they go to a brake contol module or something? so thats where I am at..lol. I thought if the pcm saw a vss signal it would shift regardless if the speedo worked or not????...idk... its confusing me because of the 4x4 stuff. What do you think??

mrvedit

I have no experience with a 4x4 nor trucks and hence cannot offer further opinion.
Perhaps Clinebarger or one of the pro mechanics here will have better advice.