Code P0340 CHK ENG LITE still on 1999 Express van

[stealthexpressvan]

Van has 160K miles. Had it for about 6 months. Trans started slipping so had it rebuilt.  When I got it back and took it for a test drive the check engine light came own and the speedometer needle pinned all the way after reaching 55mph.  Took back and they said that error coded showed bad bad cam shaft sensor.  They replaced the sensor and the check engine light went back on again.  They replaced the sensor again and same thing happened. Brought van to second mechanic.  He diagnosed 1-2v instead of 12v in sensor wire. Took harness apart looking for a broken wire and found nothing. I went to pickup van today after they re taped harness and it will crank but not fire.  Any thoughts on this? The second shop referred me to another shop for electronic analysys.

A couple of sided notes.  The heater control resistor was burned out and the vehicle may have been jump started or battery charged with reversed + and -

 

[Weight]

My thoughts. The first shop, the transmission shop, should get this fixed for you. Sounds like they messed up. Any good shop will admit their mistakes. You need a good trouble shoot to find the problem. Could be the third time's the charm.