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Discussion Starter #1 (Edited)
Alright guys, recently my "Service Soon" light has been coming on. So this afternoon, I retrieved the trouble codes from the ECU, via the C.C.P. So, I've got two codes...26 and 38.

26=Shorted Throttle Switch Circuit
38=Open MAT Sensor Circuit

I have a a vauge to no understanding of these two items. What in the world are these things, what should I do about them. This is not the best running Eldorado, but I'm sure any hinderance I can take from it will be well worth it! Thanks in advance fellas (and femmes!)!:hmm:

UPDATE:
I just ran a "Engine Data" test and all the parameters checked out normal, except:

Parameter .0.5 Manifold Air Temperature Normal range: -40 to 151...I got -18 (engine off) and -20 (running). To my recent understanding, the MAT sensor will short/go out and "make the ECM think you're in Alaska". And it would seem my MAT sensor is very messed up. Easy, I'll order and replace that sensor. I have yet to find out any more about that Shorted Throttle Switch.
 

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Sounds like your throttle position sensor is not getting 5VDC power or it's grounded internally, it's a threee wire potentiometer with the other two wires being feedback & ground reference.
Pull the harness plug & check the signals. If OK, then replacing the TPS would be the next step.
 

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White Diamond '03 DHS (with DTS floor shift)
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I don't think the TPS is ever refered to as a switch. I wonder if it is refering to the switch on the ISC motor. What (if any) symptoms are you having? Oh, wait aminute, 85 Eldo. Yikes, it's been so long since I've had my head under the hood of one of those I'm not sure if it even has an ISC motor. No longer have a FSM for it either. Sorry.
 
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