The Ground on ALL Vanagons is negative.  
Be sure to remove the ground strap from the chasse and clean well with a wire brush, and use Di-Electric grease before reconnecting.  
A good ground is critical for optimal performance.  
Also, check other ground straps by transmission, starter etc. do the same.  
Inspect ALL positive wires for any nicks, since corrosion can get inside the wire, causing resistance and improper signals from sensors to ECU.
A good idea to do this especially when a vehicle is stored outside in the elements.

Following these procedures will help insure a "positive" experience when you venture out.

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of Michael Kimball
Sent: Saturday, April 18, 2015 9:39 AM
To: vanagon@GERRY.VANAGON.COM
Subject: Battery ground

Does the 87 Vanagon have a positive ground elec. system