Thread: glendayle's 99 Buick Regal GS

Put in coolant and loaded new injector settings. Starter her up for a few minutes and she sounds good. Didn't have time to take her for a spin/scan yet. Tomorrow!

Finally getting close. Couldn't figure out why my voltage was low as the alternator was testing good as well as the battery. Ended up being the voltage regulator. Went to the JY, pulled an alternator and put it on and same issue. Bad voltage regulator. So, ordered a Bonneville 140 amp alternator off of ebay used for pretty cheap. Installed it last night. Totally plug and play but the harness was stretched super tight to be plugged in. I decided I didn't like that so I spent about an hour rerouting the alternator wires in front of the SC. Hopefully I can tune this thing. Oh well, one day at a time. I've been out of town about 17 days out of the last 3 weeks. My wheel fund has been slowly building up as I've been selling stuff. Maybe I'll get to order those in the next week or so.

Having another small issue. Reverse lights are always on when headlights are on and will not come on(even if in reverse) when headlights are not on. According to the GM manual, it is likely a short in circuit 24 which goes out of the "backup lamp relay". I have no idea where this relay is. Any help appreciated.

Clint...I'll look up the circuit tonight when I stop into my place. Shoot me a message about 330pm EST

Originally Posted by BillBoost37

Clint...I'll look up the circuit tonight when I stop into my place. Shoot me a message about 330pm EST

Thanks,
I'll shoot your a text. FWIW, for fun I tried plugging in a different relay just to see if it was a bad relay and the relay doesn't appear to be the issue.

Ok.. there's two different schematics. One for vin K and 1 the other for M. I guess maybe M was .. a 3.1? Either way.. sticking to our schematic, there's nothing in the circuit that relates to the headlights.



Goes right from the BCM. Which questions..is your bcm having issues.


System Description

The Body Control Module (BCM) diagnostic system check is an organized approach to identify problems associated with the BCM. The BCM diagnostic system check must be the starting point for any BCM-related complaint. The BCM diagnostic system check will direct you to the next logical step in diagnosing the complaint. The BCM is a very reliable component and it is not likely the cause of the malfunction. Most BCM system malfunctions are linked to faulty wiring, connectors, and occasionally to other vehicle components. Understanding the BCM and using the diagnostic tables correctly will reduce diagnostic time and prevent unnecessary parts replacement.
Diagnostic Aids

•	Use a J 35616-A when probing or checking electrical connector terminals. The J 35616-A prevents terminal damage, plus checks for proper terminal contact tension.

•	If the BCM malfunction is intermittent, refer to Intermittents and Poor Connections for more information.

•	Exit all scan tool tests before cycling the ignition switch to off, unless indicated by the scan tool. Follow the scan tool user's manual. Failure to follow these instructions may set DTCs, cause vehicle system malfunctions, set false DTCs, or cause scan tool malfunctions.

•	DTC P1626 will set in the Powertrain Control Module (PCM) when the ignition switch is on with the Body Control Module (BCM) disconnected. When BCM diagnostics and repairs are completed, refer to Engine Controls for additional information on PCM related DTCs.

Test Description

The number(s) below refer to the step number(s) on the diagnostic table.

1. Determines whether the Class 2 serial data link has a circuit malfunction or the BCM is not communicating with the scan tool.
   
2. Tests for a short to ground in circuit 2340.
   
3. Tests for an open in circuit 2340.
   
4. Tests for an open in circuit 1550.
   
5. Tests for an open in circuit 1037.
   
6. Tests for a faulty BCM.
   
7. Tests for BCM current DTCs stored in memory.
   
8. Tests for BCM history DTCs stored in memory.
   
9. Tests for an intermittent BCM system malfunction.

Step	Action	Value(s)	Yes	No
1	Turn the ignition switch off. Connect a scan tool to the Data Link Connector (DLC). Turn the ignition switch on. Using scan tool, attempt to establish communication with the Body Control Module (BCM). Refer to Scan Tool Diagnostics for more information. Does the scan tool establish communication with the BCM?	--	Go to Step 15	Go to Step 2
2	Using scan tool, attempt to establish communications with these vehicle systems: • Powertrain Control Module (PCM) • Instrument Cluster • Electronic Brake Traction Control Module (EBTCM) • SDM and HVAC (w/CJ2) Does the scan tool communicate with the vehicle systems listed above?	--	Go to Step 3	Go to Step 9
3	Test the BCM-PWR fuse. Is the BCM-PWR fuse open?	--	Go to Step 4	Go to Step 5
4	Replace the BCM-PWR fuse. Turn the ignition switch off. Turn the ignition switch on. Test the BCM-PWR fuse again. Is the BCM-PWR fuse open again ?	--	Go to Step 10	Go to Step 5
5	Turn the ignition switch off. Disconnect the BCM connector C3. Using a test light, connect between the BCM harness connector C3 terminal B and ground. Is the test light on?	--	Go to Step 6	Go to Step 11
6	Using a test light, connect between the BCM harness connector C3 terminals B and D. Is the test light on?	--	Go to Step 7	Go to Step 12
7	Disconnect the BCM connector C2. Disconnect the scan tool from the DLC. Using a DMM, measure the resistance between the BCM harness connector C2 terminal B5 and the DLC terminal 2. Is the resistance within the specified range?	Less than 2Ω	Go to Step 8	Go to Step 13
8	Reinstall connectors/components removed. Turn the ignition switch on. Using scan tool, attempt to establish communication with the BCM. Does the scan tool establish communication with the BCM?	--	Go to Step 15	Go to Step 14
9	The scan tool is unable to establish communication with vehicle systems because of a Class 2 serial data link circuit malfunction. Refer to Diagnostic System Check - Data Link Communications in Wiring Systems for the diagnosis and repair of the Class 2 serial data link. Is the action complete?	--	Go to Step 1	--
10	Repair short to ground in circuit 2340. Is the repair complete?	--	Go to Step 1	--
11	Repair poor connection or open in circuit 2340. Is the repair complete?	--	Go to Step 1	--
12	Repair poor connection or open in circuit 1550. Is the repair complete?	--	Go to Step 1	--
13	Repair poor connection or open in circuit 1037. Is the repair complete?	--	Go to Step 1	--
14	Replace the BCM. Refer to Body Control Module Replacement for more information. After replacing the BCM, perform the Setup New BCM procedure. Refer to BCM Programming/RPO Configuration for more information. Is the repair complete?	--	Go to Step 1	--
15	Using scan tool, Test for BCM current DTCs. Refer to Diagnostic Trouble Code (DTC) Displaying for more information. Are any BCM current DTCs present?	--	Go to Step 16	Go to Step 19
16	Write down BCM current DTC(s). Using scan tool, Test for DTC history DTC(s). Refer to Diagnostic Trouble Code (DTC) Displaying for more information. Are any BCM history DTCs present?	--	Go to Step 17	Go to Step 18
17	Write down BCM history DTC(s). For each BCM current DTC, perform corresponding diagnostic table. Refer to Diagnostic Trouble Code (DTC) List/Type for more information. When dealing with several current DTCs, start with DTC with the lowest number, then proceed to the next DTC with a higher number until all current DTCs are diagnosed and repaired. For each BCM history DTC, go to corresponding diagnostic table and read the circuit description. Refer to Diagnostic Trouble Code (DTC) List/Type for more information. When dealing with several history DTCs, start with DTC with the lowest number, then proceed to the next DTC with a higher number until all history DTCs are reviewed. History DTCs deal with intermittent malfunction that may not be present at this time. Attempt to repeat the malfunction by following the suggestions listed in diagnostic aids. Each diagnostic table gives information on the criteria that the BCM uses to set the DTC. This information will help you locating and fixing the condition that caused the intermittent malfunction. Is the action complete?	--	Go to Step 1	--
18	For each BCM current DTC, perform corresponding diagnostic table. Refer to Diagnostic Trouble Code (DTC) List/Type for more information. When dealing with several current DTCs, start with DTC with the lowest number, then proceed to the next DTC with a higher number until all current DTCs are diagnosed and repaired. Is the action complete?	--	Go to Step 1	--
19	Using scan tool, test for BCM history DTC(s). Refer to Diagnostic Trouble Code (DTC) Displaying for more information. Are any BCM history DTCs present?	--	Go to Step 20	--
20	Write down BCM history DTC(s). For each BCM history DTC, go to corresponding diagnostic table and read the circuit description. Refer to Diagnostic Trouble Code (DTC) List/Type for more information. When dealing with several history DTCs, start with DTC with the lowest number, then proceed to the next DTC with a higher number until all history DTCs are reviewed. History DTCs deal with intermittent malfunction that may not be present at this time. Attempt to repeat the malfunction by following the suggestions listed in diagnostic aids. Each diagnostic table gives information on the criteria that the BCM uses to set the DTC. This information will help you locating and fixing the condition that caused the intermittent malfunction. Is the action complete?	--	Go to Step 1	--

Looks like there is a picture that didn't display. these instructions look a little bit different than the diagnostic info I have. There are no codes that my little homemade tool is pulling. I may have to drive over to AZ.

Here is what I was looking at.

There's also a page for inoperative. You said they go on with headlights and nothing else turns them on. Then I went after the BCM diagnostic. Cause it's mentioned in the inop etc flows.

Here's the thing.. you are having them turn on/off when they shouldn't. BCM gets an input to turn them on/off. BCM commands the relay so the question is.. is the BCM getting an input when it shouldn't, or is it just outputting when it shouldn't?

Originally Posted by L84BngoRacing

Hi Clint =)

um......Hi LOL

Did you fix it yet?

Originally Posted by BillBoost37

There's also a page for inoperative. You said they go on with headlights and nothing else turns them on. Then I went after the BCM diagnostic. Cause it's mentioned in the inop etc flows.

Here's the thing.. you are having them turn on/off when they shouldn't. BCM gets an input to turn them on/off. BCM commands the relay so the question is.. is the BCM getting an input when it shouldn't, or is it just outputting when it shouldn't?

Yeah, I understand. I don't know if I have the proper diagnostics tool to do this. I drove over to AZ to have them check for any codes and there wasn't any. BUT....I have an additional issue now. The shifter will not move out of park. It's like the car does not recognize that the brake is being pressed. I'm thinking that these issues are related. I couldn't find the diagnostics check for this issue, but I'm starting to think that it's either the shifter position sensor thing, or the BCM is bad.

Well.. you know how to check that!

http://www.grandprixforums.net/how-a...ion-49297.html

Use that guide where it shows the line and dot to check it. Always check in neutral

OK, Interesting. On the picture that shows the 7 pin connector, it shows circuit 24 as the backup lamp feed. It also shows also there is a park/neutral signal as well. I guess I'm a little confused by what I need to be checking. Obviously, my trans already has the PNP switch. Are you suggesting that it's out of alignment and needs to be adjusted? or that it needs to be replaced. I was thinking it was the piece/harness under the shifter, but you are indicating the other switch that is on the trans.

You said shifter position sensor.. and the link is to that sensor... you just had everything in a billion pieces and .. I dunno what was or wasn't done. Check to see if you are getting a bad feed out of the trans switch, then find it at the bcm and then see what's up on the output from the bcm

What is that sensor called that is connected to the shifter. It's basically below the manual shifter release mechanism.

Sent from my HTCONE using Tapatalk 2

I'm not sure. What's your FSM say it's called? I've never looked it up.

I think I may have gotten confused. Where the manual says "range selector" I thought it was refering to that shifter plug. Sounds like it meant the PNP switch that you discussed. So it looks like I'll try that and set the position from your writeup. Do you have the info for "Backup lights system check". I can't find it in these manuals. Good thing about these manuals is they have about everything. Bad thing is the origination and the table of contents isn't great so sometimes I have trouble finding things.

Yeah..I do have some stuff on it. Everything you already found and that BCM test. The bcm controls the relay... so either the bcm is telling it to kick on improperly or it's getting an input to turn it on when it shouldn't.