99 C5

The other day after days of rain. I couldn't get my car started after I parked it. I tried jumping it no luck. I pulled the battery and had it tested...it had only 440 cranking amps so I replaced it car started right up. Until I came back again. This is the message I get everytime.

Reduced Power, Low fuel, Check engine soon, scrolls across the screen and the door locks, seat memory and ignition won't work until I disconnect the positive and reconnect it again. Then the car starts, but I have to do this every time I drive the car.

I have cleaned the connections really good and nothing seems to work.

 

This is the second one of these I had to answer this week!

See if your door controls function correctly

This is going to sound stupid but:

Open BOTH doors and find the rubber accordion tube between the doors. Collapse the tube with your fingers and feel for the two wiring harnesses in the tube. Pinch the harnesses and shake the hell out of them. Then see if you have the same symptoms.

BC

 

Crazy stuff!

I turn my own wrenches, yet know nothing about wiring diagrams. This kind of thing worries me when I need electrical help 20 years from now with my '01Zo6. Who would have known the answer to that question?

 

I did what you said in the doors. It did do anything. Your are right about the windows not working when it happens. I have some power, but not alot. I can disconnect the ground on the battery as well and reconnect and it fixes it to get it started. I think I am going to try and clean the grounds today and see if that helps. If anyone has any suggestions it would help. This is very frustrating.

 

I found this look over pass post and I am exploring now. It rained so much I had water dripping into my drivers seat and the floor did get wet. It did short out my driver seat control becasue water dripped on to it. My carpet is wet under the seat. I am going to pull the seat out and look, but could this be giving my the issue with the car not wanting to start. I have clean grounds and they all look good. I have wiggled the wires in the doors. Any thoughts

Next area:

The seat control module plug/s (under the passengers and or drivers seat) can get damaged and short out. Examine the electrical plugs and look for broken, shorted burnt or corroded wires.

Let us know what you find

Bill Curlee

 

Sure enough I found blue corrision in the two plugs under the seat. I have now disconnected them and cleaning them up. I am going to let the car sit for the next few hours and see if it will start with out disconnecting the battery. So maybe I found it. This rain needs to leave Florida.

 

Crap I am ready to give up. Its still not starting with out disconnecting the battery and reconnecting. The codes I am getting as Current codes are 1000 1064 1160 1176 any thoughts.

 

You need to include the LETTER designation in front of the code (P-XXXX and then include the suffix. (C and or H)

Don't give up so fast.

BC

 

After clearing all the old code and making the car not start again. I pulled these codes

U1000 H C
U1064 HC
U1160 HC
U1176 H C

Maybe this will help

 

Ok,,,lest do some experimenting. Un-plug your drivers seat (Set it where it will fit you) See if that resolves the issue.

If not, Disconnect the battery, remove the BCM. Once its removed,,,examine all the pins i the connectors and make sure that there not corroded or damaged. If there good,,,open the BCM box (yep, it will open) remove the one screw on the bottom and remove the board. Examine the back of the board and look for corrosion. If you have any, use a dry scrub brush to remove the corrosion and then wipe with alcohol.

Here is what the board looks like:





Be careful. The board is ESD sensitive. Make sure you don't static shock it.

Examine the printed circuit board wiring runs and make sure none are damaged.

If all looks well button it up just like it came out and put her back in.

There are TWO small thin grey connectors next to the BCM. They are the STAR connectors. ALL the serial data from all the modules run thru those connectors. You can remove the tops of those connectors and inspect the connectors for corrosion. The tops is a buss tie bar that connects all the pins together.

If you find nothing there, if it were me, I would disconnect every module from the car except the BCM and PCM. Then see if it does the same thing. Something is causing the BCM to fail to communicate with the other modules. Thats why your getting all those U series codes.

If all of this fails, you may in deed have a bad BCM.

There expensive so, do what you can do to prove it bad.

BC

 

I pulled it out and found nothing. The connections all looked good no marks on the board. I have the seat out and disconnected. Still issues. It does say in the computer - BCM not communicating. How do you test the BCM.

 

You dont! Thats the issue. I would how ever test ALL the BCM things that can be tested There are like 3 fused 12 VDC inputs ( Hot at all times, Hot ignition ON, BCM-1 BCM-2. You need to check ALL of them for correct operating voltages. There are also BCM grounds that need to be checked. I will look in the service manual and make the list.

Unless you have access to a GM TECH II, theres not much more you can do other than replace it. Its expensive and it must be programmed with the Tech II if there are any special RPO codes from the factory.

If the module is replaced theres a BCM / PCM sync procedure that must be accomplished befor the car will run. Thats why I said troubleshoot it to death before you decide to replace it.

BC

 

I had a friend come by today with a better scaner and we pulled this code P1518 PCM to TAC.

I found this searching what are your thoughts of it being http://forums.corvetteforum.com/c5-t...ch-repair.html

What are your thoughts on it being the ignition switch?

 

Not sure if it is good news or bad news. I have all the seats unplugged. The wires in the doors unplugged. I have cleaned most of the gounds and not finding much in corriosion. But instead of going dead after about 5min it is taking about 1 hour. Any other thoughts would help. I am running out of area's to explore and I have search the forms over and over. This has been a week of Hell.

 

Today I found 2 things and was wondering if anyone had any thoughts. The ground on the passagers side door behind the seat sparks when I connect and disconnect it. It makes the anntena move a little bit so I pulled the tail light and the gound where the antena is with a ribben cable is very rusty any thoughts. Why would this ground spark?

 

The antenna motor runs until it meets mechanical resistance then the armature shifts and breaks a mechanical switch contact. It does this in both positions. When it breaks the switch contacts, it sets up the circuit to allow it to travel in the opposite direction when directed to.

When you remove the ground, you cause the Radio Power Antenna module to energize and the coil inside the module powers up and tries to make the motor power to the correct position. It's normal.

If the ground connection is rusty, clean it with a wire brush, soak it in PB BLASTER and try to remove it carefully and clean it then reinstall and apply a corrosive protective compound to the area

BC

 

Tanks Bill. I did all that yesterday. I have now cleaned every ground, pulled wires out of the doors. Had the ignition apart and the car still is having the same issue. I think the next step is to change out the BCM. Its the only think I can thing of left to do after tryng everything for over a week. The BCM does click when we reove the battery cable and reconnect it and the car will start but afet about 15 -30 min something happens and there is no commuication any more with the BCM.

 

Check your clutch switch if its a manual.

 

Have you pulled out the BCM circuit board and checked it out? Before you throw in the towel, I would do that. Also pill the caps off the serial data buss STAR connectors and check them.

The only place you haven't looked is at the PCM. Make sure that there isn't any wiring damage from past battery acid spills. Theres a removable access panel in the passengers fender well. Remove it and give that area a look.

Bill

Ahhhhhhhhhhhhh,,,you already said that you did that. But do check the PCm wiring and the PCM.

 

I did remove the battery and the box. I have checked all the canon plugs next to the battery. I have not check the PCM. I asume it is the box you can see with the battery shelf out. I will pull that access pannel in the morning.

Thanks