Sensors? Sensors? Sensors? Under dash

[Guest wally888]

Need help to identify 3 sensors under dash top panel.<BR> Two on bracket(accessable by removing Defroster grille) and 1 attatched to underside of dash.(not accessable w/o removing top dash panel)<BR> Attatched sensor has part # of Sun Load Sensor but manual identifies another as Sun Load Sensor.<BR> Is one Twilight sensor and if so why do I have or need it as I have no twilight switch?<BR> Have all removed and code 115(sunload sensor)Tested Data -22

[Guest wally888]

R R R ,<BR> I searched the manual till almost blind,don't know how I missed 201-10 as I looked a t 11! Have code 115 and got data and snapshot w/ in tolerance but always resets after clearing.Ordered new sun load sensor. Also held match to sensor no change in reading. Hope it ain't open in ground.<BR> I have all three sensors in the car and couldn't figure out why twilight as I kept looking at 8c-14,figure 18.While writing I<BR>this I finally figured out what HDLP means.<BR>Figure doesn't show Inside air temp. sensor and guess I overlooked the connecter(shown)Gettin old ain't much fun!

[Guest]

From what I can gather, the early Reattas did not have the Twilight Sentinel option. If the car has this option, the light switch will have an extra slider potentiometer above the standard dash light slider potentiometer. The manual shows how to enter diagnostics to measure the resistance of the photocell in bright light and dark conditions. My BCM always gives error "B119 Current", which is the Twilight Photocell, even though I believe my car doesn't have a Twilight Sentinel.<P>The Service Manual will answer all questions regarding location and operation of all the sensors. Part 8A-201-10 of the 1989 Manual shows the Sunload Sensor mounted at the top center of the dash on a bracket with one screw with the In Car Temperature mounted directly below the Sunload Sensor. Another way to identify which is which is to find the sensor in the Wiring Diagrams of the Service Manual and note the wire colors of the particular sensor in question. Page 8A-68-1 shows the In Car Temperature Sensor has Dark Geeen and Black with Pink Tracer wires. The Sunload Sensor has a Light Blue with Yellow Tracer and a Black with Pink Tracer wires.<P>The temperature sensors are thermistors, a resistor that changes resistance with temperature. The sensors can be measured using an ohmmeter. If the sensor is in a convenient location, the wire harness plug can be disconnected for a resistance reading. For hidden sensors an inter-body, BCM, or ECM connector may be removed and the resistance reading taken. <P>Most all sensors, switches, motors, lights, and engine functions can be diagnosed through the ECM or BCM from the comfort of your driver's seat without having to disconnect any electric cal item. Just use the on board Driver Information Center. <P>The Reatta is one of few cars made where sophisticated troubleshooting can be performed by the owner. The 1986-89 Reatta, Riviera, Toronado and possibly one or two more GM cars had this feature. No more.