delsol54 Posted June 17, 2017 Share Posted June 17, 2017 I have a 1990 Reatta I bought last fall that received a beautiful blue paint job by me over the winter. Now I am trying to get the rest of the issues fixed so I can enjoy it. I found that the cruise didn’t work so after much research I believe it was two issues , one a vacuum hoes (easy fix) and two a servo because I have an open between pin C and D, there should be 40 or so ohms there. I haven’t gotten a newer one yet. Also had a O2 sensor that was bad which I found with a check engine soon light on and the respected code in the ECM which is now fixed. Which now bring me to the real issue. Engine light is back on. For some reason which I cannot explain, I cannot read the ECM when I jumper out pin A and B. engine light is on after pulling the battery for an hour and it ran afterwards for an hour at idle and a short drive to reteach the ECM. Still when jumping out A and B I get nothing, no flash, no nothing. I also tried to read the codes in the BCM by pushing off and temp up/down on the heater controller but nothing, no zeros in the odometer no codes. I also have no tech, no speedo, and no temp, which all worked at one time. PS help I’m not sure where to go from here or to replace an ECM. Any ideas.. :huh: Link to comment Share on other sites More sharing options...
Ronnie Posted June 17, 2017 Share Posted June 17, 2017 Welcome to the forum! I'm not as familiar with the '90 as I am with earlier models. Since the '90 doesn't have a CRT touch screen don't you have to have the speedometer working to read the codes? Maybe the instrument panel has gone bad. That is a common problem on the '90'91 models. Link to comment Share on other sites More sharing options...
delsol54 Posted June 17, 2017 Topic Author Share Posted June 17, 2017 Everything worked fine before i read the BCM by pushing off and Temp at the same time. and i was able to read the BCM. the check engine light came on and i tried to read those code by jumping out A and B at the plug , but like i said zero, nothing happened. them i tried to read the BCM and nothing. this is the time the speedo and other didn't work. it did and then it didn't. very frustrated :huh: Link to comment Share on other sites More sharing options...
Ronnie Posted June 17, 2017 Share Posted June 17, 2017 I've never shorted the ALDL pins to read the codes. Do you think you might have accidentally shorted the wrong pins causing a problem? Link to comment Share on other sites More sharing options...
Ronnie Posted June 17, 2017 Share Posted June 17, 2017 Many have said that leaving the cover off the ALDL connector can cause problems with the computers talking to each other. IF the cover is off, install it and see if it makes a difference when checking codes with the onboard diagnostics. Link to comment Share on other sites More sharing options...
delsol54 Posted June 18, 2017 Topic Author Share Posted June 18, 2017 Many have said that leaving the cover off the ALDL connector can cause problems with the computers talking to each other. IF the cover is off, install it and see if it makes a difference when checking codes with the onboard diagnostics. A and b pins are the two pins to short out and I can't get into the on board dia. Link to comment Share on other sites More sharing options...
Ronnie Posted June 18, 2017 Share Posted June 18, 2017 If you have disconnected the battery for a while and still can't read the codes there must be a problem with one of the computers. Maybe someone will respond that has experienced this problem. I don't know what to tell you. Link to comment Share on other sites More sharing options...
Aztec62 Posted June 18, 2017 Share Posted June 18, 2017 delsol54, please do not try to read error codes by trying to short two pins at the ALDL connector. This will not work on a 1990 Reatta. You must leave the ALDL cover on, too. There are two pins inside the cover wich will make a connection across two pins of the ALDL. This connection is essential for the communication of the various computers of the Reatta (ECM, BCM, Instrument cluster and so on.) Is the instrument cluster of your Reatta OK? Or is it showing an error with the ignition on? Have fun Henning Link to comment Share on other sites More sharing options...
Frogware Posted June 18, 2017 Share Posted June 18, 2017 Also the shorting of the A and B pins on the ALDL connector is for reading the codes for the ABS not the check engine light. As said above reconnect the ALDL cap and if your IPC is working then you should be able to read the codes. I believe you are pushing the wrong buttons (I did the same thing) here are the instructions to read the codes http://www.reattaowner.com/roj/component...-91-models Turn on the key and on your ECC ( climate control module ) push the "OFF" and temperature up ( up arrow ) at the same time and hold them until the car goes into the diagnostic mode. Link to comment Share on other sites More sharing options...
delsol54 Posted June 19, 2017 Topic Author Share Posted June 19, 2017 1st i want to say thank you everybody for your help. and also, who at GM decided to put a jump in the cover of the ALDL should work for Ugo. I've been involve with cars for 50 years and that's a first, with that said, let me start fresh again and tell you where we are. after putting the cover with jumper on the ALDL, and disconnect the battery for an hour while i ate dinner all to start at the beginning. with that said, i started the car again. this is the results. air conditioning fan runs ( did before but failed to mention) Check engine light on , temp gauge worked momentarily then didn't ( about 1 second before starting the engine) , speedo and tac doesn't work also. let engine run for awhile but never seemed to teach itself. turn engine off to read the codes from the (Climate control mod) ( push off and up arrow ) for which seem like forever and nothing , no flash no nothing. now remember a few days ago everything worked , the temp speedo, tac and the engine ran very good. i was trying to debug a problem with the cruise and i was able at that time to read the codes. So what the heck happened, did i somehow blow the ECM or the BCM or both. i thought id meant my match when the headlight switch ( with fog lights) fell apart in my hands and a millions parts landed on the bench. two hours later after studying the hundreds of parts including disc, springs, tiny little terminals and a handful of what knots, i got it back together without extra parts and it actually works saving me $400 bucks, but this engine/dash/ecm has got my goat and i don't know what to do. pls keep the comments coming ty don ( delsol54) Link to comment Share on other sites More sharing options...
Ronnie Posted June 19, 2017 Share Posted June 19, 2017 Don, Do the idiot lights along the bottom of the instrument panel work as they should? Is the rest of the instrument panel (speedometer, tach, etc.) dark or are they just not showing a reading or anything when the engine is running? What happens when you press the TEST button on the instrument panel? Link to comment Share on other sites More sharing options...
Ronnie Posted June 19, 2017 Share Posted June 19, 2017 Just for the heck of it move the dimmer slider on the headlight switch to the right so the IPC (instrument panel) is in the full bright position. Link to comment Share on other sites More sharing options...
delsol54 Posted June 19, 2017 Topic Author Share Posted June 19, 2017 the rest of the dash works as it should. all the light work and pushing the test button illuminates all the lights. the speedo tech and temp light up but there is no reading, I'll readjust the dimmer slider in all position in a few minutes but not sure way or what your looking for here. Link to comment Share on other sites More sharing options...
Ronnie Posted June 19, 2017 Share Posted June 19, 2017 If your IPC looks like the one in the photo below when you press the test button it proves there is nothing wrong with your IPC. That is the first thing that needs to be ruled out - even though it was working before. The reason I ask about the dimmer is this: If you have a bad twilight sensor (photocell that senses day and night and automatically dims the IPC) AND the dimmer slider is all the way to the left, the IPC could be so dim that you can't see anything on it. A bad photocell on the Reatta is a common problem. Again, this is something that needs to be ruled out before doing more troubleshooting. http://zombdrive.com/images/1991-buick-reatta-3.jpg[/img] Link to comment Share on other sites More sharing options...
delsol54 Posted June 19, 2017 Topic Author Share Posted June 19, 2017 pls to report all works as it should in the test mode, and the dimmer works as well, bright enough to see everything there . seems like it's point to the ECM. Link to comment Share on other sites More sharing options...
Ronnie Posted June 19, 2017 Share Posted June 19, 2017 Let me look at the service manual and I'll get back to you. I really don't think the problem is the ECM. In the meantime... Does the temp gauge still work sometimes? Also, you might want to clean the climate control panel to rule that out as a problem. How To Clean 1990 Climate Control Panel Link to comment Share on other sites More sharing options...
Ronnie Posted June 19, 2017 Share Posted June 19, 2017 After looking at the '90 FSM (Field Service Manual) I think the next step is to check fuse #5 CPS (Central Power Supply) and fuse #9 HVAC to make sure they are good. Fuses And Breakers - Console Location Also do the interior lights come on when you slide the dimmer all the way to the right? Link to comment Share on other sites More sharing options...
delsol54 Posted June 19, 2017 Topic Author Share Posted June 19, 2017 all the fuses in both panels have been ohm out and are good. no issue here. the interior light do not come on when the dimmer switch sides all the way to the right. this could be a malfunction of that switch. Link to comment Share on other sites More sharing options...
delsol54 Posted June 19, 2017 Topic Author Share Posted June 19, 2017 all the fuses in both panels have been ohm out and are good. no issue here. the interior light do not come on when the dimmer switch sides all the way to the right. this could be a malfunction of that switch. the temp gauge only reads when you first turn the key to on for only a split second. Link to comment Share on other sites More sharing options...
Ronnie Posted June 19, 2017 Share Posted June 19, 2017 Do you have a service manual for your '90? Link to comment Share on other sites More sharing options...
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