If you have 3/4 of a tank of gas but it suddenly reads empty and wont start sounds like a bad body control module really common on that car.I have replaced tons of those body control modules on the 2000-2004 L model saturns.You can check the fuses but i doubt you will find anything there.The first thing i would do is use a scan tool that can read the body control module on that car if you cant talk to it most likely its a bad body control module.I have replaced so many of those body control modules on those cars i have one bad one to fit each of the L models for 2000-2004 for testers.

Thanks. Never heard of a body control module. And who decided that we need one, cars are too complicated these days. I don't have a scanner. Any other way to check it? Where is this module, and what does it look like? If it is an expensive item?

RSVP?

Still waiting for your reply.

The way it was explained to me by a few car engineers i have met is the consumer drives all the new car gadget hype.Every year the consumer buying cars or cell phones etc are looking for new features etc.Also the government has a impact on that also so the engineers scramble to put something out.Unfortunately if isnt proven which a lot of it isnt then the consumer is left with repairs cost etc.Heres a great example in 1997 gm started leasing the gm ev1 in california and airzona.Saturn was told to lease service and market the car.I went to factory gm ev1 training its a gm impact that was un,veiled in the early 1990's at the auto show.I met all the engineers that designed the car at the training for car.We would leave class each day and go back to our hotel room and replace a good 15 pages in the service manual.The fit and finsh was terrible they even made seal update kits so the door seals would and fit better.They constantly broke down average repair bill was 800-1200 which was under warranty gm lost a lot of money on that one.The government pushed that one because like 1 or 2 percent of there fleet has to be zero emissions.Talking with the engineers that made the car they said they had 6 months to turn a prototype car into a production car.It had 27 batteries seven computers and over 500 trouble codes.Something would fail and set 50 trouble codes in 3 or more computers.It was hit and.miss fixing them because there wasnt any proven repairs and failures.Your body control module controls the shifter interlock keyless entry door locks anti theft fuel gauge temp gauge just to name a few.Its mounted to the top of the glove box cant miss it.Do you have a pick a part by you?Also a new one is in the mid 200's if you buy it online and it has to be programed at a gm dealer for mileage options etc.

We are on the internet this is instant message where iam waiting for your message to reply.We are people who volunteer our time to help people like you in our spare time.So you may get a reply right away or it may take a while depending on how busy iam doing something else.I know your car is not running and that you want it running as soon as possible i get that.Also your talking to the right person iam a factory trained saturn tech.

Thank you for the insight. Leave it to the buying public, and the government to foul things up. Sounds like the Space Shuttle in the early days when Rockwell ran the show. I'm from the days of points/plugs/and condensers. I remember my neighbor setting the points on his old Pontiac with a match book, nothing complicated about that.

Yes, there is a U-pull it near by where I can look for a body control module. Again, fuel gauge pegged at empty, and no sound from the fuel pump when the key is turned on, not even when the starter is engaged. Hope another BCM fixes the problem.

Best regards,
gr

One other question, can I use a junk yard BCM from another year Saturn or must it be a 2001? And will it have to be programed by a dealer?
Thanks again,
gr

Heres where the hard part comes in you will need to find a 2001 4cyl engine L model saturn there year and engine specific on those.I would only use a used one for testing only they store the mileage in so what ever milegae is on the donor car will read on your car from it.Plus to start the car the pass lock will have to be relearned.But if the gauges etc work you will know the body control module is bad.Also i had a 1969 caddy loved that car hated the points installed a petronix electronic ignition conversion with a high output coil what a diference in idling starting running.With 10.5:1 compression doesnt run so well on points.

I posted the pass lock relearn procedure for you so you can start the car to drive it to get a new one installed and program.Also a used bcm can set off the abs air bag light etc.

Thank you again. I will look for the same year and engine configuration in the junk yard tomorrow. Then, if I understand you correctly, I will have to use the relearn procedure to be able to start the car. Is this a one shot deal, or must I use it every time the car is started? Is the junk yard unit only for testing and must it be replaced with a new unit? If the only down side is an incorrect odometer reading I can live with that. I don't care about the mileage reading, and I don't think the state will either since the car is over ten years old.

These new(er) cars certainly are techie, and require a whole different set of skills to figure out. That's the downside for me, but on the other hand they go a lot longer between tune-ups and the engines last a lot longer. Cars used to end up in the junk yard before reaching one hundred thousand miles, today I'm driving a 1996 Silverado with 260,000 and all indications are that it will go a lot farther. Only failures have been a intake manifold gasket, water pump, alternator, and upper ball joints. Everything else was on the truck the day it left the factory. (other than normal wear items like brakes and tires)

Best regards,
gr

No once you learn the pass lock your good to go you may have to have the used bcm programed if you have lights come on etc.The mileage change is federal not state so best to tell dmv about it.Also i know i cant find many L model cars in my pick a part so you may have to find one on ebay.Let me know if you have anymore questions.

Will do, and thank you very much. You da man!
All best,
gr

Your welcome thats what were here for please keep me posted with how you make out.

Hi Saturntec9,
Just installed a junk yard bcm, same year same engine. Fuel guage still reads empty. Turned ket to run position, then a fast hit on the start position. Security light flashing for quite a while, then steady until off at about tem minutes. Doing the second cycle now, two minutes into it and the security light is flashing.

Not sure if the fuel guage was supposed to be working as soon as the new bcm was installed. If so the ecm is not my problem, because I still do not have a reading on the fuel guage. Is that correct?
gr

Lets finsh off the pass lock learn and see if it starts up the gas gauge should be working now but the real wild card is how good the tester bcm is?All my tester bcms are labeled what they were doing when i replaced them.You said the gas gauge stopped working when you had 3/4 of a tank of gas and there was a no start.I have tons of bcms do that when the bcms failed.Thats why i have the testers to check if the bcms are bad before putting a new one in.ALso thats why i suggested scanning the bcm for codes etc a lot of times when they fail the scan tool cant talk them ethier and that is a another indication of a bad bcm then i would put a tester bcm in and see if the scan tool could talk to that one.In your case we have to just improvise the best we can.So was the security light on when you had the other bcm in?Have you checked any fuses yet?Like i suggested you could do in a earlier post?Can you hear the fuel pump kick on when you turn the key to the run position for a few seconds?

Alright, I went through the pass lock sequence three times, then tried to start the car, no joy. The guage still reads empty, I did not hear anything from the fuel pump. I really don't remember if the security light was on with the old bcm, but I don't think it was.
I checked fuses and relays yesterday. One question, while doing the sequence, where the directions say to "Wait ten minutes" is the key supposed to remain in the on position? I figured that it did, otherwise you wouldn't know when the security light went out.

I did notice that after completing the third cycle, when I turned the key on, the security light did not come on until I engaged the starter.

Maybe I should try the sequence again?

Lets do this while cranking the engine see if you have power to both sides of the fuel pump fuse?

Okay, checked for power at fuse with key off, got 12v on right side of fuse socket. Cranking with meter across fuse socket, nothing.

I guess I'll perform the relearn procedure another time, see what happens.

There should only be power to fuel pump fuse while the key is first turned to the run position plus cranking and while the engine is running.You can try the relearning again but if the security light isnt on when first turning the key to the run position then there is no way to do the relearn.See if you have spark a nice blue spark?

There is power to the fuse with the key in the off position. The last time I turned the key to the on position there was no security light. The light does go on at first turn of the key along with all the other indicator lights, then turns off in a few seconds. Checked for spark...nothing.

I did get another bcm from a car that was a year newer, a 2002, should I try that? Does pulling the bcm give me another shot at relearning the computer?
gr

I guess I'm stalled at this point, it's 11:30PM here and I'm sure you're finished for the day. I will be away tomorrow and unable to continue until I return home on Saturday. Don't know if you're available on the weekend, but please message anything you think I should try next. Thanks for your help, will message you when able.
All best,
gr

I dont know why you got the 2002 bcm like i said before has be the same year and engine to work.Unplugging the bcm will not give you another shot at relearning the pass lock sensor.How did you check for spark?Did you pop up coil cassette and have it plugged in with spark plugs in it touching the head while cranking the engine looking for spark?Also with the key in the run postion see if you have a 2 ohm or less to ground on the black wire to the ignition module and see if you have battery voltage to the pink wire to the ignition wire?

I'm still stumped, tried everything you suggested several times. Must be you're out for the Holiday? RSVP with any ideas when you are able.
Thanks,
gr

Please answer the questions i asked right above your last post?

I did answer it several post back, but to rehash, I got both the 2001 and a 2002 just because it was there and I figured what the heck. I only installed the 2001. There is 12V on one side of the pump fuse even with the key off. I have 12v on the pink wire and under 2 ohm on the blact to the ignition module.

I also jumped between number 87 and 30 on the relay and the pump goes on.

I'm wondering if the security feature is my problem now? Is there any way to relearn the BCM after having done it before?
Thanks,
gr

Tuesday morning 11AM Eastern, still no progress on getting the car to start. Any hope for me to get this sorted out myself? It's looking like I'll either be towing it to GM or to the junk yard, and taking it to the dealer is likely to cost more than what the car is worth. Anything else I can try?

Heres the tough part you dont have a scan tool when can read live data on the engine and body control module.That way we can see how both those computers are working plus see what the data values are.Also its strange that you dont have power to both sides of the fuel pump fuse while cranking.Did you try swapping the relay with another one?Also try testing the crank shaft position sensor with a ohms meter its on the block facing the radiator.See what the ohms reading is?

Okay, just got back home and read your post. You haven't given up, that gives me hope! Here goes. I just checked the power at the pump fuse, got power on both sides, key off, as well as while cranking. Not sure how or why, but that is the status at this time. I've swapped the relay several times, I even have an old relay with the plastic cover removed, I can plug it in, squeeze the contact together and energize the pump. Still no fuel guage movement even while doing that. I did get the guage to read half to three quarters (correctly) at one point the other day while trying to pull the relay out. I've opened the fuze box looking for any loose wires, corrosion, nothing apparent. Next I'll check the crank position indicator ohms, as soon as I can locate it.
Thanks again,
gr

I think we stumbled on something here sounds like the problem is in the fuse box where the relay is if the fuel gauge poped up while moving the relay around.I would pull the fuse box out and look at the connectors for open terminals you will see the terminal openings going into the fuse box sometimes there are open terminals that have been that way since the car was built.Then one day it starts causing issues try pushing on the fuse box while watching the fuel guage?ALso post some pics of the terminals on the harness side?Also you looked for white corroded terminals on the harness and fuse box side correct?

I opened the fuse box a couple of days ago, right after the pump and fuel gauge came to life. I thought I had found the problem, tried to start the car, and no luck. I tried dozens of times to duplicate the occurrence, but never could. I opened the box, pushed on all the wires to make sure they were going into their respective spots, nothing seemed to be amiss. There wasn't any evidence of corrosion anywhere, but I even squirted an aviation anti corrosion treatment into the sockets just to be sure. I'll open it up again and look closer to see if I missed anything. I even treated any of the grounding points that I was able to see in the engine compartment. I never worked on a Saturn before, so everything about it is unfamiliar to me. Should I still check the crank position indicator ohms? I am still wondering if the security circuit is keeping it from starting. The security light doesn't stay on after turning the key on, it illuminates for a few seconds then goes out. Not really sure if the replacement BCM is doing it's thing, seems to me that something has the ignition shut down. Never did get spark when checking for it the other day.

With no spark fuel gauge etc thats not anti theft that will only disable the fhel.injector pulse.If you were moving around the relay and the gas gauge starting working i would be looking at the fuse box and connectors.Did you look for open terminals on the harness going to the fuse box?

Checked out the box several times, can't see anything suspect. Haven't looked at the connectors on the harness, but I will do that now. I will uncouple them and look at the terminals.
Thanks,
gr

Please post some pics of those connectors.

Not too sure I know how to do that. I will have my son help me with that when he gets home.

Sounds good.

I opened the fuse box again, took a photo of the inside, and a photo of the only connector that I could unplug with a bundle of wires that go to the box. (along the firewall) There are connectors inside the box on the left side, but on the outside there are only wrapped bundles of wire, no connectors. There might be connectors inside the top portion of the box, but I can't see how to seperate it from the lower part. I didn't want to break anything prying it apart. Now I've got to try to get the photos out of my camera and onto this website.

I attached photos, two of the fuse box, one of the only connector I could see that goes to the box. Let me know if I am missing something, because I can't find any other connectors.

Well, after much head scratching I finally figured out how to take the "connectors" apart from the top of the fuse box. Duh...when you told me to look at the connectors I really didn't know what you meant, and I looked for connectors in the wiring harness going into the box. I told you that I didn't know how to seperate the top of the box from the bottom, and didn't want to pry on it and possibly break it. It took me a while but I figured it out myself, undolted the plugs and viola! Here are two photos, and everything looks okey to me. Will treat with anti corrosion and put it back together. What next?

PS Adding photos was easier than I thought it would be