slvrzo6

I went to Lunch Yesterday in the 2001 Z06.. After Lunch the Car acted like it didn't want to start... After the Car Starts the DIC says. Charge System Fault.. Then a bunch of messages. Reduced Engine Power. Service Traction Control. Service ABS.. Low Voltage and then Back to Charge System Fault again..

Took my Battery to Autozone. OPTIMA RED TOP, They checked it and Charged it, Battery is ok.. Got the Car home, Checked Battery Wires and everything else I could. Went here to the Forums. Checked my Codes, P1518 H C was the only one.. Something about a Serial link From PCM to TAC.. I Reset the Codes, Checked wires again.. Somehow got the car started without codes??? Drove straight to the Dealership to ask them... Now the car is at dealership, It wouldn't even start and the DIC still says, Charge System Fault and is in reduced power Mode with Code P1518 until the Corvette Tech can look at it monday.. Any Ideas would be greatly appreciated!

Bill Dearborn

DTC P1518
Circuit Description
The throttle actuator control (TAC) module and the powertrain control module (PCM) communicate via a dedicated serial data circuit. This serial data circuit is separate from any other serial data circuit on the vehicle. Accurate transmitting and receiving of serial data requires not only good circuit integrity, but also adequate system voltage. This diagnostic monitors the accuracy of the serial data transmitted between the TAC module and the PCM. If the PCM detects a loss of data or invalid data, this DTC sets.


Diagnostic Aids
DTC P1518 sets if the battery voltage is low. If the customer's concern is slow cranking or no crank because battery voltage is low, ignore DTC P1518. Clear any DTCs that may have set from the low battery voltage condition from the memory.

• DTC P1518 sets when there is a short to B+ on the TAC module ground circuit. Inspect the fuses for the circuits that are in the TAC module harness, such as the cruise, or the brake. An inspection of the fuses may lead you to the circuit that is shorted to the TAC module ground circuit.
• DTC P1518 sets if the TAC module ignition feed circuit is shorted to a B+ supply circuit. The TAC module stays powered-up when the ignition switch is turned off. When the ignition switch is turned on, the TAC module is powered-up before the PCM. DTC P1518 sets because no communication is detected by the TAC module from the PCM. Inspect related circuits for being shorted to a B+ supply circuit.
• Inspect the TAC module power and ground circuits and the TAC module/PCM serial data circuits for intermittent connections.
• Inspect the TAC module connectors for signs of water intrusion. When water intrusion occurs, multiple DTCs could be set with no DTC circuit or component conditions found during diagnostic testing.
• When the TAC module detects a problem within the TAC system, more than 1 TAC system related DTC may set. This is due to the many redundant tests that run continuously on this system. Locating and repairing 1 individual problem may correct more than 1 DTC. Keep this in mind when reviewing captured DTC info.

Interesting, about how long you are waiting for somebody to look at the car. If I took the car in yesterday without an appointment my dealership would have already called me with the results of their diagnostics and the recommended repair.

Bill

KCvetteowner

I would still look at the battery especially if it's at least 3 years old. You mentioned Autozone charged it, why? If the battery was good it shouldn't have needed a charge. Maybe your alt is not charging properly or a wire is loose on the alt?

A lot has probably happened since your first post, hope everything was painless but when a dealership is involved that's usually not the case. I took mine to a dealer once and they wanted over $200 to install a new battery. I picked up a new one at the local auto parts store for $60 and walked right through their service bays to my car parked in back. Within 10 minutes I drove back through the service bays with a big smile on my face...

slvrzo6

My Battery is one year old.. Bought at Autozone so that's why I took it there. Yeah, Car is still sitting there, waiting till monday for the CORVETTE TECH!!.. I didn't plan on leaving it there, Since I got it started I wanted to know what they thought of the problem.. BAD Idea I guess. Cuzz if the Car was here I'd be messing with it..

KCvetteowner

I'd go back and try to get it started but then I work on my own cars. Do you know anyone that knows about alternators that could help you? Sounds like yours might have headed south but that's a guess.. If they call and say it needs an alternator go online and get a price for one at a local auto parts store and tell them to do a "competitive price adjustment" since you found one for $$$.

Wish I still lived in Decatur, I'd help you out...

slvrzo6

Yeah, if they say it's the Alternator or a simply module I'll do it my self, But I have a feeling it's something else? Maybe? Or could it be that simple? I just guessed that the Code P1518 HC it was something else more serious?!?!

slvrzo6

This Sucks!! My car has been at the Dealership for almost a week now!! They actually called me Today... I guess they have made NO Progress with my Car. Car is still in reduced power mode and shows Code P1518HC. The Corvette TECH checked all the grounds, All the Wires at the starter, They said he also checked voltage and several different points on the car and PCM. They said nothing was constant. They said the TAC Module was good. So their TECH had a call into GM technical support????? GREAT I feel like my Car is F**K'D.. She told me there TECH had 6 hours working on it just today.. GREAT at like 80 an hour are they going to hit me for a $480.00 bill for nothing being fixed??? They also checked the Serial Cable from the TAC to PCM and voltage at several more points ? I guess it just shows Code P1518 HC still? Can anyone help me? I told them to Try putting a different Battery in, just to see if my OPTIMA was doing weird stuff. She said they would in the morning and call me again.. JEZZZZ this is a downer! Can anyone Help me??

homewrecker

ttt

MattB

New battery is what I'd do, the red tops can be tempermental and once they get that far gone they are toast. IMO I would get something different than a red top.

freddykaye

I have an 02 Vette with the same problem code, Only after the first time low voltage, reduced power, service stability control and traction control comes on if I let it run for 2 min in reduced power, shut it of and restart it, it runs fine but check engine light is on. drive it for a couple minutes, shut it off, restart immediatey and check engine light goes off and everything is fine. till next time i drive it then let it sit for 30 min and it starts all over. 3 month old battery. replaced the battery and everything is fine again, even though the old battery checked out good. go figure...

ZZ06

Im no electrician by no means. However i have owned my 01ZO6 for 7 years and have been a part of this community for a while. I understand the tech checked the voltage. The fact that you said autozone CHARGED that battery only after a year says problem. They should have not had to charge that battery unless the battery is bad or you have a severe drain and pull somwhere while the car is off. I still would replace battery with somthing else. Not the first thread ive seen where an idividual had electrical problems with an optima red top. Seems some are good, others are not.

65GGvert

That was 6 years ago, he's probably tried the battery by now.

ZZ06

.....aw boy. Ive been in the desert too long

65GGvert

It does help to note that at least some people who have been having intermittent issues with Optima's is not a new thing.

Bill Curlee

Sounds like you could have a corrupted serial data buss issue. Heres what I would do:

Go get your car. Open BOTH DOORS. Grab the rubber accordion tube between the door and door frame. Feel for the wires inside the tube and pinch them between your fingers. SHAKE THE HELL out of the tube and wires and see if the issue goes away.

Clear the DTCs and see what you get. You may have to do that procedure a couple of times. You can also find the STAR BUSS CONNECTORS to the left of the BCM.





Fine the one with four wires and pop the top (shorting buss) off the top of the four wire connector.

That isolats the LDCM, RDCM and SCM from all the other serial data wires/lines.

I have a stinking suspision that you have lost control of the door functions on one or both doors also..

Anyway.. Give that a try and see where that gets you.

I will PM you my cell Call me...

Bill

laurent_zo6

You're not crazy. You were answering post #10 from 09/11/2014. (That's your story and you better stick to it)

ZZ06

freddykaye

Well im embarassed... can ya tell im a newbie? lmao.. I searched the forum for answers, maybe I should check the dates... Thanks