Yesterday I posted the problem with the knock sensor and today after cleaning the fuel injector connectors I have a new code I've never had before, 1-4-4. This is a bad signal from the Regina module to the Rex module, the Rex module being the electronic box under the coil. I have checked everything I can find and cleaned the connections (none of them seem corroded). I am wondering if there is a pattern failure associated with this code. Has anyone seen it before on your car and if so, what was the fix?
Thanks for any help you can give me.
Dan

 

I have been taking so much stuff apart and reading so many wiring diagrams I am dreaming about this car. I found the problem though, it was the 8 pin connectors strapped under each side fender brace near the hood hinges. Volvo calls these C55 and C50. The soft plastic retainer, that a terminal pushes into from each side, is made to tightly grip both sides to keep them from coming apart. That stuff is disintegrating. This allows the female terminals to slide in and out freely.
So, when you pull it apart (disconnect) the male terminals pull the female terminals in to place where they should be and it looks perfect. When you put the two halves together the male terminals which are fairly secure, push the females to the back of the connector instead of pushing inside them. The connector is deep enough that you can't see any evidence of this happening unless you shine a light directly in the back and their locations make it difficult. So at first you twist the connector a little and everything looks OK and you move on.
I had the Regina computer in the right kick panel out and disconnected and the Rex module above the steering wheel the same. Measuring continuity between the ends of the yellow wire showed there was a break somewhere, which eventually led back to the connectors.
I cut the connectors out and used solderless terminals to join each of the wires.
So.......that wasn't much fun
Dan

 

Be thankful it was a relatively easy fix on a 90. On my 84 the insulation was biodegrading...not just the rubber connectors..On 20+ year old Volvos, poor connection are at least equally responsible for idiosyncrasies as are failed components IMO...