During a fault finding mission on my car I found the Vref on a sensor that should be 5V sitting over 7V. I traced it back to one of the modules and found the pcb mounted voltage regulator was outputting the 7V I'd seen at the sensor. The reg was a LM2931-5.0 fixed voltage regulator in TO-92 config.
In doing some research on the specs I thought it may have failed due to engine bay heat and replaced it with another LM2931-5.0 TO-220. I changed to the TO-220 as it had better heat handling characteristics. The problem is that the new reg is now passing the full 14.5V through. I tested continuity at the pins and there is no shorts.
Has anyone got any ideas why these regs aren't dropping the voltage to 5V as they should? The pins are slightly larger on the second reg and took some force to install. I wondered if I'd damaged it doing this but I thought it that were the case I would see a short between them.