4L60E weird shift and speedometer issue

[Goats86]

I have a friend with a 2005 5.3/4L60E. Several weeks it started having odd shifts(late, hard, etc). Then this am the speedo was reading about 80 mph when she was only driving about 30 and read over 100 when on the highway. It sounds to me like the VSS may be going bad, giving the ECM bad info and causing the odd shifts and now speedo issues. Has anyone had this issue or be of guidance where to look? Thanks in advance.

[clinebarger]

Originally Posted by Goats86

I have a friend with a 2005 5.3/4L60E. Several weeks it started having odd shifts(late, hard, etc). Then this am the speedo was reading about 80 mph when she was only driving about 30 and read over 100 when on the highway. It sounds to me like the VSS may be going bad, giving the ECM bad info and causing the odd shifts and now speedo issues. Has anyone had this issue or be of guidance where to look? Thanks in advance.

Is the Check Engine Light on? If so, Have it scanned and post the codes.

If the VSS was reading "high" it would shift early, You need to scan "live" VSS data to confirm a bad VSS.

The VSS produces a A/C voltage signal, It can not "gain" output. When a VSS fails it STOPS working or intermittently stops working.

I bet the speedometer problem is in the cluster. GM has a extended warranty on them....Contact a local dearler if your truck has under 80,000 miles.

[502ms]

I know not related in brand, but I have experienced this with my 1991 Acura Legend automatic. When the VSS was dying on me, it had erratic shift patterns, speedo flopping up and down, and just bad drivability. I put my money on the VSS being faulty
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