My 98 won't start, low voltage on dash
 

Hello
been browsing this forum from time to time but never really had the chance to stop in and say hi. Now that my 98 won't start I am hoping someone here can give me a little help. I promise, i just won't come here to use this forum for the help.
My 98 just started acting up yesterday, barely got it home.
When I put the key in and go to turn it over the car will not start, the engine turns over but will not fire. It starts popping up all these messages on the dash display, LOW VOLTAGE, REDUCED ENGINE POWER, SERVICE ACTIVE HANDLING, ETC. and now this morning SERVICE ENGINE SOON. I can hear this buzzing sound from under the hood, that sounds kind of "sickly" for lack of better word. And the strange thing is when i use the turn signals, either up or down I can hear a buzzing sound and the turn signals will not work. The battery is good, just changed it, dome light works good and under the hood light in the engine works good. Also they key FOB (think thats what it is called) will not work, won't lock, unlock, or even pop the trunk. This all started happening at the same time.
The voltage for the battery at the dash is barely showing 8 volts, however it's fully charged at 12.7 under the hood.
Any help you could give would be appreciated. hate to take it to the shop if it's something i can take care of and hate it even more not really knowing what it could be.
Thanks

RE: My 98 won't start, low voltage on dash
 

why did ya change the batt ? use a good DVOM and put the probes on the batt and check volts,then probe the hot term .next to elect center,it should have a red cap on it.it sounds like a bad connection,but just in case have someone try to start the car while you look a the meter as its connected to batt

RE: My 98 won't start, low voltage on dash
 

It could possibly be a ground problem. There are two connectors under the hood, behind each headlight. Unplug these and inspect them / clean them, if needed. I would also remove the battery and battery tray and inspect under the battery location for any signs that acid previously leaked down into that area. This is common on C5's and will cause problems.

CG

RE: My 98 won't start, low voltage on dash
 

Thanks for the replies. Actually i put an optima battery in the car, there was nothing wrong with the old one but it was 4 years old so just thought I would upgrade to the Optima.
I'll check things out with a volt meter again but haven't found anything out of the norm yet and I'll check those grounds out...
Thanks again

RE: My 98 won't start, low voltage on dash
 

From my experience, when it says "low voltage," it's time to replace the battery. There are some radar detectors out that will also display low voltage, meaning the same thing...battery is ready to sh-- the sheets.

RE: My 98 won't start, low voltage on dash
 

Where exactly would those connectors be? Under the headlights as your looking into the bay? So far the battery tests out fine, even under load. The Optima battery is brand new. When i turn the key on nothing on the dash moves, usually all the gauges will move FULL right than back to normal readings, now nothing. The tray is clean under the battery, no acid leaks

RE: My 98 won't start, low voltage on dash
 

Yea, I thought the obvious also, but the battery checks out fine

RE: My 98 won't start, low voltage on dash
 

Well i am starting to wonder whether it is the VATS system. My understanding of this is the chip in the key hasa certain resistance, this resistance is detected and sent to the VATS decoder module, which basically says, resistance is fine, Ok to start.
I was in the garage checking things out and troubleshooting it, I kept inserting the key in the ignition and turning it on, off, on, off, and I was finally able to get the car started....

Where is this VATS decoder module located?

RE: My 98 won't start, low voltage on dash
 

:eek: From your original post, it is difficult to determine but..........Did the problem start right after you swapped out the battery or was there a period of time AFTER the install of the new battery where all worked as it should???

Looking for "cause/effect"

RE: My 98 won't start, low voltage on dash
 

The ground connectors are under the hood, right behind / in front of (depends onyour point of view)the hood struts. You cannot miss them. There are gray / black connectors with black wires coming out of the back.

I doubt that it is the VATS. VATS would only prevent the car from actually starting (starter would not turn over / no fuel to injectors, etc).

CG

RE: My 98 won't start, low voltage on dash
 

The battery was in about a month, than this happened.

RE: My 98 won't start, low voltage on dash
 

Thanks CG
That makes sense about the VATS.

I am believe it may be the ignition switch, I don't have full voltage at the fuse when the ignition switch is ON. I will be replacing the ignition switch this weekend and will let everyone know how it turns out...
Thanks for the replies

RE: My 98 won't start, low voltage on dash
 

You gotta' getta' wiring diagram, and find out where the power and ground is for the circuit that controls the items indicated on the system console.

GM in the late '90's (and maybe earlier, and maybe early 2000's), have several electronically-controlled items on one 'circuit'. For example, my '98 GMC (GM) has one circuit called circuit 1020, which is 4 wheel dr controller, tranny controller, dash guages, and a few other items also. If you lose power to the circuit, codes for each item light up, even tho' each item works fine.

You gotta' get the wiring diagram. Before buying haynes or chiltons, go to the public library and check their copies.

You can do it yourself, OR, pay the dealer to do it.

RE: My 98 won't start, low voltage on dash
 

Why you gonna buy a new ignition switch?

RE: My 98 won't start, low voltage on dash
 

Check condition of bat cables, at both ends. Clean if corroded and replace if any breaks show.

RE: My 98 won't start, low voltage on dash
 

JUST THOUGHT I WOULD LET EVERYONE KNOW IT WAS THE IGNITION SWITCH. IT WAS DIFFICULT TO TROUBLESHOOT BUT FINALLY FIGURED IT OUT. I WAS GETTING FULL VOLTAGE AT THE BATTERY BUT ONLY ABOUT 9 VOLTS SHOWING AT THE DASH WHEN I WOULD TURN THE KEY ON. WENT TO THE FUSE BOX ON THE FLOOR BOARD AND CHECKED VOLTAGE THERE AND FUSE 19, I BELIEVE FOR THE STARTER/SWITCH CIRCUIT WAS ONLY SHOWING 9.2 VOLTS WHEN I TURNED THE KEY ON, THUS INDICATING A BAD IGNITION SWITCH. I IMAGINE THE CONTACTS WENT BAD OR SOMETHING IN THE SWITCH ITSELF. PICKED UP A NEW SWITCH AND 2 1/2 HOURS LATER IT WAS FIXED. JUST TO CHANGE THAT SWITCH I HAD TO PULL THE DASH PANEL OFF, THE KNEE BOLSTER PAD, THE CENTER CONSOLE AND THE WATERFALL.... QUITE A CHORE, ESPECIALLY WITH THAT DASH PANEL.
I WOULD BE WILLING TO BET THIS WOULD HAVE COST ME ABOUT $600 AT THE DEALER.
SO IF ANYONE SHOULD HAVE A SIMILAR PROBLEM, KEEP THIS IN MIND.
THANKS FOR THE REPLIES! :D

BTW....THE SERVICE MANUALS I HAVE CAME IN VERY HANDY.

RE: My 98 won't start, low voltage on dash
 

I like you have not been here in a while but if your still having problems respond,and Ill send you some info that helped me. But like I read someone else state that this is a common problem among C5's

RE: My 98 won't start, low voltage on dash
 

Thanks, I did get it figured out. It was the ignition switch and ended up changing it out myself and saving quite a bit of money that way. Bet the dealer would have charged a pretty penny for it, as there was quite a bit of labor involved just getting the switch out.

RE: My 98 won't start, low voltage on dash
 

Ignition switch failure is common in GM products. One way to check in the future is check voltage @ gauges fuse with the key on.