Good morning, Have been reading posts on this forum about splicing in the series 2 PTU, and understood all the content provided by Vadar and other members, on our install on the weekend on first crank of the engine PTU went extremely hot and engine wouldn't crank, so we stopped, I have double/triple checked all colour wires match ups and pretty confident all in right place. but because we haven't changed anything we are assuming car wont crank and PTU will get hot again so don't want to repeat process until I understand what might be happening. The series 2 PTU was purchased second hand and only assumed it was a working unit as no paperwork came with it, not sure if they can be verified as a working unit or I can test at home. Any suggestions, appreciated. Mary Background we purchased our 90 TT 2+2 5 years ago, spent lots of time and $$ getting her back to her former glory, original PTU started mucking up so thought we would do the swap over, wanted to buy new plug and drive system, unable to find in stock so went for the second hand unit and had to splice it in to original wiring loom, 80% sure I followed wiring diagram.