Ron Walker Posted July 31, 2021 Share Posted July 31, 2021 My CRT gave me a reading of "Engine Controls Problem Detected - Engine Controls Computer has detected an electrical problem." I downloaded the "How To Access ECM, BCM & CRT Codes" written by Ronnie and/or Padgett and tried viewing the codes on the CRT. Pretty detailed, but not sure I understand what I'm looking at. I have an appointment with my Chevy dealer to look at the diagnostics and to troubleshoot and/or correct the problem. My Buick dealer refused to get involved by saying that they have no experience with a Reatta??? The only symptom that I'm aware of is that at idle in Park, the engine will run for a few minutes and then "shut off." I can restart, the engine will run, and will drive seemingly with no problem if at speed. If driving at slow speed next to an idle, the engine has shut off. Any thoughts? Also, concerning the on board diagnostics capability. Down by the emergency brake pump pedal, there is a grey box that states "Diagnostic Connector - Do Not Remove." Is this an auxiliary OBD diagnostic connection? If so, will it give the same information as the CRT diagnostics? Link to comment Share on other sites More sharing options...
Ronnie Posted July 31, 2021 Share Posted July 31, 2021 As soon as you enter diagnostics by holding the OFF and WARM buttons at the same time on the climate control screen, you should immediately see any codes that are stored in diagnostics start being displayed on the CRT. Be ready to write them down because they will scroll by pretty fast. The ones you will be concerned with right now are any codes the begin with an "E" and have three numeric digits following it. Let us know if you have any codes and we might be able to help. Link to comment Share on other sites More sharing options...
Ron Walker Posted July 31, 2021 Topic Author Share Posted July 31, 2021 I'll check again and re-post. Any thoughts on the auxiliary OBD diagnostic question? Link to comment Share on other sites More sharing options...
Ronnie Posted July 31, 2021 Share Posted July 31, 2021 Dealerships in the '80 and '90s probably had diagnostic scanners that would interface with the Reatta computers via the ALDL connector and some OBD 1 scanners would work if you could find one. As long as the CRT is working I see no need to use the ALDA connector other than to check ABS codes. I think the Reatta onboard diagnostics will tell you as much most scanners. 1 Link to comment Share on other sites More sharing options...
Ron Walker Posted July 31, 2021 Topic Author Share Posted July 31, 2021 Thanks. Rechecked the CRT codes, and the first (and only) "E" code shown was "E034 History." Based on your chart, E034 description is "MAF Sensor Voltage Low." Is there anything else to diagnose the problem? What is the cure for the MAF Sensor Voltage Low? Link to comment Share on other sites More sharing options...
Ronnie Posted July 31, 2021 Share Posted July 31, 2021 I don't remember anyone ever having that code before. I read the FSM and it seems to be saying the ECM isn't receiving a proper signal from the MAF. The FSM does have a testing procedure but it isn't really a simple one that could be described here. If you have a FSM check section 8D1-46 for testing instructions. If it were me I would clean the electrical connection to the MAF, clear the codes, and wait and see if the engine control warning and code comes back. 1 Link to comment Share on other sites More sharing options...
Ron Walker Posted July 31, 2021 Topic Author Share Posted July 31, 2021 Good point. I will follow the cleaning suggestion and then wait and see. I don't have an FSM. I note in the "How to Guides - Computers & Sensors - Mass Air Flow (MAF) Sensor Cleaning" cautions about the use of non-approved cleaners. Is there a specific cleaning solution recommended for the cleaning process? I presume my dealer should know, but...... As to the ALDL connector, I now see that discussion in the "How to Guides - Diagnostic Instructions." Your point above offers a succinct explanation as to the benefits of the CRT diagnostic capability. Link to comment Share on other sites More sharing options...
Ronnie Posted July 31, 2021 Share Posted July 31, 2021 The only product I have used is the CRC Mass Air Flow Sensor cleaner. It did a good job and didn't cause any problems. Just be careful that you don't touch the sensor with the spray nozzle and damage it. I would use contact cleaner on the MAF electrical connector that is safe for use on plastics. Most of the contact cleaners for automotive use are. 1 Link to comment Share on other sites More sharing options...
Ron Walker Posted July 31, 2021 Topic Author Share Posted July 31, 2021 Another question - how do you clear the codes? I didn't want to experiment before I let the dealer see the code, but it's not intuitive. Link to comment Share on other sites More sharing options...
Ronnie Posted July 31, 2021 Share Posted July 31, 2021 There are two ways to clear codes. You can disconnect the battery cable for a couple of minutes and then reconnect. That will clear all ECM and BCM codes at the same time. Sometimes that is the only way to clear all the codes, like when the AC compressor gets locked out because of low Freon and you can't get the compressor to run to add Freon. You can also clear codes in diagnostics. After all codes are displayed you will be asked ECM? Press YES. Then you will be prompted to enter several areas of the diagnostics like "ECM DATA" etc. Press NO. Keep pressing NO until you see the prompt "Clear Codes" and press YES. All ECM codes will be cleared. If you happen t have to have BCM codes you will have to go through the same process for the BCM. It takes a while to get use to using the onboard diagnostics. Keep playing with the diagnostic until you get familiar with it. You can't hurt a thing. The overrides have built in safeguards that will keep you from doing something really stupid. 1 Link to comment Share on other sites More sharing options...
Padgett Posted July 31, 2021 Share Posted July 31, 2021 BTW this system is NOT OBD, it is ALDL - same thing just GM proprietary. Under the "do not remove" cap is an ALDL connector. I have a couple of OTC 2000 scanners with Pathfinder cartridges and GM cables (check eBay). If you want to go even deeper, everything you need for ALDL is at Moates.net. You will need an ALDL >USB cable, TurerPro RT software, and a Windows tablet or laptop. To reprogram you need the C.A.T.S. tuner software with the 5B definitions. To go really deep will need ALDLStuff.zip 1 Link to comment Share on other sites More sharing options...
Ronnie Posted July 31, 2021 Share Posted July 31, 2021 1 hour ago, Padgett said: BTW this system is NOT OBD, it is ALDL - same thing just GM proprietary. Thanks. I didn't realize that. I have always referred to it as ODB 1. I had assumed ALDL with the type of interface GM used. Link to comment Share on other sites More sharing options...
Padgett Posted July 31, 2021 Share Posted July 31, 2021 Assembly Line Data Link: is a serial (CCC was 600 baud, P4 (Reatta) is 8192) LAN that ties all of the devices in a car together. Is redundant in that it makes a big loop around the car so that if any one device fails it still works (why the under dash access port says "Do Not Remove", it completes the loop). Could go on for a few hours about serial LANs (not 802.11). Won't. 1 Link to comment Share on other sites More sharing options...
Ron Walker Posted August 1, 2021 Topic Author Share Posted August 1, 2021 Yeah, I saw those two pins that stay in the cap that says "Do Not Remove." Figured that had something to do with the loop. Noticed in the "How to Guides" about connecting a wire to the ALDL to close the loop if the cap is removed when doing some trouble shooting. I removed it to count the pins since it didn't say "under penalty of law...." Thanks for your help and comments. Link to comment Share on other sites More sharing options...
Ron Walker Posted August 6, 2021 Topic Author Share Posted August 6, 2021 Well, cleaning the MAF didn't work. I'm waiting for the dealer to get me an OEM MAF sensor for install. Also, appears that the catalytic converter is failing, and that will be replaced (with aftermarket). Following clearing the codes, in addition to E034 (MAF Sensor Voltage Low), the CRT also now shows E041 (Cam Sensor Circuit). What would be the cure for the E041? Deterioration in engine performance has become marked. Low engine rpm is rough idle and stall. I must keep the rpm above 2,000 to discourage a stall. To and from the dealer means slip the tranny into neutral at red lights and revving the engine. Link to comment Share on other sites More sharing options...
Ronnie Posted August 6, 2021 Share Posted August 6, 2021 48 minutes ago, Ron Walker said: the CRT also now shows E041 (Cam Sensor Circuit). What would be the cure for the E041? Padgett has done a great job of explaining what is causing, and how to fix, a code E041. Read about it here. However, the rough running and stalling isn't likely to be caused by the Cam Sensor. The engine should run decent even when the cam sensor is disconnected or when the magnet that triggers it has fell out. 1 Link to comment Share on other sites More sharing options...
2seater Posted August 6, 2021 Share Posted August 6, 2021 If you don’t have the new MAF yet, try disconnecting it and see if the engine performance improves. I don’t mean a performance enhancement but better behavior. 1 Link to comment Share on other sites More sharing options...
Ron Walker Posted August 12, 2021 Topic Author Share Posted August 12, 2021 I'll give it a shot and report further. Link to comment Share on other sites More sharing options...
Ron Walker Posted August 12, 2021 Topic Author Share Posted August 12, 2021 Because it's so late and raining, I only removed the electrical connection to the MAF and didn't take it out onto the hi-way. Performance remains lousy. The whole car shakes at idle and improves only slightly when I rev up to above 1,800 to 2,000 rpms. The replacement MAF sensor hasn't arrived yet (at least no call from the dealer yet. Last time my appointment was advanced 2 weeks due to, reportedly, a lack of technicians. So it will be a while before I post results of the replacement. Link to comment Share on other sites More sharing options...
Padgett Posted August 12, 2021 Share Posted August 12, 2021 Just said on another thread but if misfiring at idle can use the override ES-10 and turn off the injectors one by one. If turning one off makes not difference in running, there you are. 1 Link to comment Share on other sites More sharing options...
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