Voltmeter is easy. If u really need one try 12volt.com. Should be a gray and a black harness w a grounding strap? Or bribe one of those best buy douche bags to give u some geeksquad techsoft.
1990 Jeep Wrangler YJ. 2.5L. Bone Stock, mostly.
"I'd have more money for upgrades if it didn't break every week."