'90... it's electric !

[ChrisWhewell]

Well, bought a '90 on 9/16, my first Reatta.  Bought it at dusk, didn't inspect it much other than the frame for straightess, drivetrain, engine.   Engine compartment is showroom new, same with paint which is all orig., and underneath the car looks brand new.  78k miles

 

it came with a basket case of a headlight on/off switch.   So, Mr. Finn has kindly provided one, I just installed the new rebuilt switch and buttoned everything back up.

 

Here's the puzzle..... turning parking lights on has no effect on exterior lighting.  Turning fog lights on has no effect on exterior lighting, but the driver's display goes dim, like really dim, almost becomes invisible, but the voltage reading on the display does not dip.   The interior dim light slide bar on the light switch has no effect on the appearance of the display.  The trunk does not open when either the key is used, or the push-button in the glove box.    When the headlamps are on, none of the 14 rear exterior light bulbs come on, and neither do any of the running lights.   Fortunately, the headlamps do light up, but the bright lights don't work, although the interior display panel indicates that the brights are on.  The electronic fuel door release is at least, functional.  Brake lights work.

 

With any luck there is a unified field theory of Reatta, and I have a single electrical fault somewhere, that when I find and fix it, everything will magically all begin to work.   hah, its too hot outside to do anymore and I've been working all week so, need to get out a little.  First thing I'll check I guess is the fuse box, maybe tomorrow...  I have a feeling this is going to be a fun one

[jonlabree]

Have you checked all of the fuses?

[drtidmore]

The first thing you really need to do is get a copy of the 90 model year Field Service Manual.  There is simply no way to guess your way around the electrical system on this car.  Virtually everything runs thru the BCM for body related actions or the ECM for powertrain.  There are relays hidden behind the interior fuse panel, relays & fuses/breakers out under the hood (drivers side toward the front) and a few in the trunk on the 90 if memory serves me correct.  

 

There could be a grounding issue.  Unlike older, non-computerized cars, there are several isolated ground as well as power busses.  The lack of rear tail lights really does sound like either fuse/breaker or relay since you have already replaced the headlight switch.  Be aware that the early 90 models shared a similar headlight/taillight design with the 88-89 models, but in a running production change, due to failing headlight switches, GM added a relay to move the headlights themselves OFF the headlight contacts.  Many of us with the older design have implemented a similar offloading to avoid ruining the increasingly difficult to find headlight switches.  I took the route of also moving to all LED in the taillight which reduced the total load of the taillight to less than ONE of the old 2057 incandescent bulbs.  

 

Once you sort of internalize the complexity of the Reatta and its systems, it gets easier to diagnose issues, but again, you will get a very bloody forehead banging against the wall of guessing. 

 

As for a unified field theory...

[Ronnie]

Replace Park light fuse. It's fuse #10 on '88-'89 models. May be different on '90 model. This might be helpful: Fuses And Breakers - Console Location

[ChrisWhewell]

I've been blessed, the 20A tail light fuse was blown.   Follwing its replacement, the fog lights work.  Also the running lights, and evidently the high-low beam functionality was impacted by that, as the issue no longer exists.   Yeehaw!!

 

Trunk latch..... relay in trunk clicks.  Pulled solenoid, it was stuck.  Lubed it, but also note that everything's painted, thick, like, there's no ground -  how did the trunk ever open from the factory on this car ?  12.24 V at the red wire so the circuitry is functional, yay.

 

At least I can get it past inspection now and have a driveable car, not bad for 2500 bucks and all I basically did was replace the headlight switch an a fuse.  Engine is smooth and has decent acceleration for an old man like me

 

What's left ??    In the underhood relay box up front, I found three Ford relays, and a thick jumper wire where the AC compressor relay is supposed to be, looks like I need some relays.   Radio ?   its stuck in perpetual casette mode, cant get it to switch over to radio.  Climate control works in auto mode but is stuck at 75degrees, which is ok when its 100 out the ac is just sufficient.   Lastly the 6-way seat adjustment, the "down" control doesn't work, probably the switch is what I hope.

 

Oddly, when I pulled the 10A fuse on the driver's side of the console that corresponds to the label "HVAC" on the fuse map with engine running, the idle kicks up about 250 rpm, and the driver's display illumination goes totally dark.  weird.  The "interior lights dim" slide bar rheostat on the headlamp switch ensemble still has no effect on the brightness of the display.  

 

Other than that "check engine light" is on, but that's no big deal, I"ll read the codes later.   RPM gauge display works first five minutes then goes dead, same with coolant gauge.  Hey I love puzzles   Thanks guys, I have a manual on the way, have a good afternoon

[ChrisWhewell]

Climate control was not working, only the fan would blow, could not adjust temperature either way.   But, I tried retrieving error codes - hold down "off" and temp-up button simultaneously, and.... it went into diagnostic mode.   Weird, that told me the temp-up arrow was being sensed.   Yet, why did it not function to permit me to alter the "set" temperature ?

 

Recall, a previous owner had put a jumper wire for the AC relay.  I pulled that jumper and put a relay in there, and then... voila - the climate control functionality has fully returned. So, if anyone has trouble with climate control not being able to adjust temperature either way, maybe check the AC relay up front for an open.  One by one, my issues going away.

 

Only error code is 041 - cam sensor circuit.  crikey, I hope the little magnet is still in place

[ChrisWhewell]

Oh, by the way.... I had previously a B334C code AND and E447.  Putting the relay in made those go away.   So, evidently, communication between BCM and ECM is subject to tripping an error code if there is no AC clutch relay in place or the elecromagnet's coil in the relay is open.