Bandit1

Got a problem with my 99 and it just started last week. I was driving to work, when the DIC indicated “Service Engine”, the volts dropped from about 14 to 11.5 momentarily and then slowly went back up. I was cruising at about 60 at the time. I watched the volts and it maintained at around 14 with nothing else happening. The next day the car ran fine until I went to go home from work and tried to start it. I turned the key to ACC I did not hear the fuel pump like usual and then tried to start it with no luck. The engine was cranking but nothing. I tried that about four times. Then I removed the key, got out, locked the car, hoping for a reset thinking it may be the anti theft module. Unlocked it, got in, turned the key to ACC position, heard the fuel pump and then started it. Drove home with no problems. Tried to start it the next morning and no-go. I interrogated the DIC this morning and got the following:

10 PCM - No Codes
28 TCS - 1 Code
-U1016H Lost Comm
38 RTH - No Codes
40 BCM - 6 Codes
-B0502H RH DRL Relay Circuit
-B0507H LH DRL Relay Circuit
-B2482H Backup Lamp Relay
-B2593H Column Lock/Unlock DriveB
-U1016H Lost Comm
-U1096H Lost Comm
58 SDM - No Codes
60 IPC - 3 Codes
-B0521H Tach Signal Circuit Malfunction
-U1016H Lost Comm
-U1116H Lost Comm
80 Radio - 1 Code
-U1016H Lost Comm
99 HVAC - 1 Code
-U1064H Lost Comm w/XXX
[B]AO-LDCM - 1 Code
-U1016H Lost Comm
A6-SCM - 1 Code
-U1016H Lost Comm
BO-RFA - 9 Codes
-U1255H Class 2 Comm Malfunction
-U1096H Lost Comm w/XXX
-U1064H Lost Comm w/XXX
-U1016H Lost Comm
-C2100H
-C2105H
-C2110H
-C2115H
-C2120H

All of the fault codes seem to be "history" and not current. After I checked the fault codes on the DIC, I turned the key off and then turned it back to the ACC position. The gauge cluster lights kept flickering, the gauge needles did not move and nothing came up on the DIC. No buzz from the fuel pump either. I had the interior floor cover off of the BCM and fuze box already and I could hear a clicking noise coming from the fuze box at the same time the gauge lights, radio, interior lights and DRLs were flickering. I traced the clicking noise to the #40 DRL L relay (could hear it and felt it on the relay). I turned everything off and pressed on the #40 DRL L relay and flicked it a couple of times with my finger. I then tried to start the car and it turned right over and ran. I let it run for approx 10 minutes and then turned it off. Went to start it again and I got the flickering gauges and lights and clicking sound from the #40 DRL L relay in the fuze box. Again, I turned everything off, pressed on the #40 and flicked it hard with my fingers a couple of times. Went to start the car and it turned right over and ran for approx another five minutes until I turned it off.

Has anyone run into this? How can a DRL Left relay control the start up/fuel? If anyone has run into this and replaced the small box relay #40, is it a simple pull out or are they soldered or screwed in? Looking for any and all opinions/direction. Got to get my baby rolling again. Thanks--John

cenzo

After ensuring a sound battery and good cables/connections, I would recommend cleaning and reassembly of G104. That's the ground located on the frame rail within the battery shroud. If that works, consider a ground restoration crusade and do them all.
Good Luck and keep us informed.

Bandit1

Cenzo-Thanks for the suggestions. The battery is sound........Optima Red Top and cables are good. Will check the G104 location, but I still think its in the interior fuze box at the BCM. Thanks again--John

Bandit1

Anybody???

Bandit1

Anybody help me out with this?

cenzo

So ... do I have to come over there? What have you done so far?
Check the BCM area for signs of dampness.
Check the ground on the engine block near the starter.
Replace the #40 relay.

Bandit1

Sure when can you get here........................just kidding. On the #40 Relay...................are these the plug in type (like fuzes) or are they soldered or screwed in?

cenzo

John, I haven't looked in there recently, but if the #40 is the same as those 1x2ish rectangular gray cans in the underhood fuse panel, it just plugs in. And if they are the same, you can swap with the horn relay from the underhood fuse panel. It takes some effort to remove them so don't be scared.

jimcork1

What is the bat voltage at no load and when the starter is engaged. I would NOT assume the battery is not bad. If the voltage drops below 10V while cranking the battery could still be defective. Keep it simple.

My guess is battery is defective with low amperage capacity and internal shorting. But then that is a guess only. best of luck. 99 Nassau Blue

Bandit1

Vince--Thanks for the info. Will let you know what happens.

Bandit1

Jim--Thanks. I will be checking the Optima again also.

Bandit1

Ok Boys............you're probably not going to believe this but here goes. Picked up a replacement relay (#40 DRL L) at the Chevy Stealer for $30. Plugged it in, turned the key to ACC, fuel pump primes, battery static volts read 12.5+, turned the key and engine turns right over. Let it idle for about 5 and turn the engine off. Wait for about 10, start the car again and everything works as advertised. Tried a couple more times and it starts every time. I don't have a schematic to do any spark chasing, but my question is what in the hell does a DRL relay have to do with the external fuel pump? The grounds, battery, battery cables, and connectors all checked out. Hopefully this is the permament fix. Thanks for all the help.

Bandit1

Well this sucks! I replaced the #40 relay and it worked for a couple of days and then it did the same thing all over again. I replaced the battery and checked the G104 ground which looked good. And it still did not want to start. Waited a couple of minutes and tried it again and it started. Shut it down after approx 5 min and started it again and it gave me "reduced engine power", "check engine" and the check engine light. I shut it down again, waited approx 5 min and tried to start it again and it turned right over. I give up. I hate to say this, but I think its time to take it to the stealer.

cenzo

It looked good!? They usually "look" good.
Best of luck with the dealer.

Bandit1

Ok, let me put it another way.......................unbolted it, there was no corrosion and mated surfaces were clean with good contact.

Bandit1

Update: My 99 Pewter is at the stealer and they can't find the problem. They did put a fuel gauge on it and found an intermittent 20lb variance in the fuel flow with an intermittent spike in the volts (14.0 down to 11.0). They think the fuel pump may be going, but are not sure. As usual, I get the car to the dealer and it doesn't do a damn thing. Anybody got any other ideas, before I pull the trigger on a possible fuel pump replacement . Thanks

Bandit1