Running diagnostic test 5 fixes electrical problem

[JedCoop]

This is the third time my BCU on my '94 Q has decided that there is a problem... my driver seat automatic movement on ingress/egress stops, and the two lights on the memory seat start to flash (and other stuff stops working, too). And twice I have run the Mode 5 diagnostic test in the FSM to have it tell me that the there is a problem with the tilt circuit. And twice the steering wheel tilt went up and down during the test. And twice all the electrical stuff in the car seemed to work perfectly again after the mode 5 test told me there was a problem. Subsequent mode 5 tests did not indicate any problems.

The only other symptom is that after egress/ ingress, the auto positioner doesn't seem to move the steering wheel to the lower position that I prefer, it likes to return to a position that seems slightly higher. And the *event* has occured after I have moved it to the lower postion, though almost all of the time I move it down there are no problems.

The first time this happened I pulled apart the steering column and looked at the tilt/telescope switch, but looked good/had continutiy. So after 6 months and this is my third of these events, it is barely a nuisance. Still I'd like to figure it out and prefer it to be fixed.

So before I go run Diagnostic mode 5 again to make the problem go away, what else can I do to diagnose this?

Thanks

[Frank's Generator]

Hello, I do not know if what I found occuring on my 92 Q45 has any bearing on your problems however it may. The quality of ground that I found as measured between the steering column metal components / the associated electrical circuits in and around it as compared to the battery negative post was excessive. I actually had 15 ohms. After running a redundant ground wire of a single #10 stranded directly from the negative battery cable end at the battery into the steering column support bolts The entire sheet metal in and around the dash is now at proper potential. My reason for inspecting this area was due to a problematic power steering control module malfunction and me finding excessive resistance at each of the two wires to the module that were supposed to be grounded. Good Luck

[texasoil]

Great diagnosis on the ground wire fault!! I think a lot of the 'weidr' electrical problems are due to bad grounds that do not get checked and fixed.

[JedCoop]

... The quality of ground that I found as measured between the steering column metal components / the associated electrical circuits in and around it as compared to the battery negative post was excessive. I actually had 15 ohms...

Thanks, you are probably on the right track. I found a 4 ohm difference from the steering column to ground, and from the ground on the tilt/telescope switch and ground. That might very with position, but I don't know.

I ran an extra ground wire to the steering column. When I ran the mode 5 test this time it did not blink any trouble code. Maybe the problem is fixed!

If I never post to this thread again, then that means success.