Does anyone understand this 3 wheel abs?

Can tire size do all this? The new tires are a little taller one in a half inch taller

I have tryed everything I can find speedometer is now double abs light now new alternator 3 new battery ends and darters cables . I’m stuck .

Does the fact it’s an American van conversion change some of the wires . I’m not finding all of the grounds . They have a different hvac unit ft and rear.

12.1 off never been more than 13.2 running now 14.2 running . And I’m still cleaning grounds . There are no flat braided grounds? Always see them all green and week on most gm products. None on rad support ?

My scanner doesn’t comm but a snap on did no codes my scanner did see abs when I got the van but not now . At the moment I am cleaning all the grounds and take a look at connections I did 5 grounds and have gained 1 volt on the gauge someone installed in side. I have the drivers side frame rail to d...

Already changed vss no other codes . My scanner won’t comm with abs but my friends snap on did no codes all looks correct till you drive it then the speedometer doubles and abs light comes on .it also stacked shifts in to overdrive at 30 mph.

I have a 1998 express 1500 the speedo doubles abs light is on no codes . I think it a ground problem where do I start? I have a stock 4 vol manual , it’s like reading a foreign language.