Doug Jacobs, a factory-trained BMW motorcycle mechanic, started Prospero's Garage as a favor to friends needing help with wiring harnesses on classic air-cooled BMWs, aka "airheads."


"A lot of guys I knew had BMW Slash 5s. Some needed help rewiring so I found some factory diagrams, made them more useful, and started sending them out." 
He soon formed Prospero's Garage as a side gig to his work as a tax accountant and made his enlarged, color-coded and laminated wiring diagrams available for classic British, German, Italian and Japanese cars, as well as BMW and Harleys. His offering expanded as time allowed and demand dictated, constrained mainly by availability of original factory diagrams used for reference. 

There are now wiring diagrams for over 550 make/models of classic European, American, and Asian cars and bikes available for immediate shipment.

Terms & Conditions

100% Satisfaction Guarantee and Other Stuff Worth Reading

We are car and motorcycle enthusiast and started this site because we happened on a good idea at the right time.  We want, to the best of our abilities, to make every customer happy – because to us, you’re a fellow car/bike enthusiast.

If you, for any reason, are unhappy with your diagram, we will either replace it or refund your money without question.

Our Error:  If we have made an error in the diagram we’ve sent you (and hey, we’re human and we do make mistakes every now and then) we will immediately send you the proper diagram.  We’ll also send you a postage paid label so that you can drop the first diagram in the mail; we’re assuming that you’ll send that one back to us.

If You Goof Up:  If you realize you hit the wrong button upon ordering, contact us as quickly as possible – if we haven’t shipped yet, we’ll substitute the right diagram.  If you get the diagram, just send it back (you pay the return postage) and we’ll send you the diagram you want (and we pay the postage to you!).

If You’re Just not Happy:  If, for any reason, you don’t like the diagram – send it back to us (you pay the postage) and we’ll refund your entire original payment.  No questions asked.

If we don’t have a diagram for your car:  Send us a note – we keep them and add cars based on demand.  If you’ve got good clean copies of factory diagrams, that goes a long way to influencing our decision to add a car to our library.  If you supply us a diagram, we’ll give you a free copy of the color diagram that we eventually produce.  That said, we’ll only do diagrams for a series of years of a car, not just a single year, and only if we think we can sell enough diagrams to warrant the effort.  Sorry, there just aren’t enough Lamborghini Urraco’s to make the effort worthwhile – even though we love that car.

Volume Discounts and Shop Discounts:  Generally, we start discounting when you buy 10 or more diagrams.  Let us know what you’re thinking and we can talk about it.  We are happy to support volume purchases by Clubs.

Donations:  And speaking of Clubs, we are happy to donate diagram certificates to your clubs raffle.  Contact us at prospero@colorwiringdiagrams.com and let us know how big your club is and when your raffle will be held.