Trolling motor wiring help

[gip50]

I have a 96 S20 Astro that i need help with the trolling motor wiring. Believe it come with 12/24 trolling motor when new. My problem is i am only getting 12 volts to plug. Has a red/white going to hot on 1 battery and a black/white going to neg. On 2nd battery has a solid red wire to hot and a solid black to neg. All 4 wires go to plug and it is a 4 prong plug and is the original plug. Seems to be hooked up as it should be. Tested plug with voltage meter and only showing 12 volts.How do i get 24 to plug? Didn't want to hook up batteries wrong and burn something up. Any help is greatly appreciated. Thanks

[BernieW]

What volt trolling motor you trying to wire in ?

[gip50]

trolling motor is 24

[Jonestrollingmotor]

On the 4 wire system, the tm plug has the jumper for 24v, else it makes through a charge run switch if equipped.

[gip50]

so its probably normal for it to show 12 volt on voltage tester at plug? When trolling motor pulls power plug jumps to 24? Thanks