1253C5

IT'S FIXED...! IT WAS THE TAC MODULE

Thanks to everyone for all there assistance...I never realized just how many friends I had.

OH IT FEELS GOOOOOOD!!

THANKS AGAIN,
Rod

OK, I know someone out there knows exactly what is going on with a 1998 C5 low miles that won't start. SO please HELP ME OUT
I posted this a couple weeks back, so here is the update as to what I have found so far, NOTHING!
The car will not fire, it turns over but no fire.
* I don't hear any fuel pumps kicking in when you first turn on the ignition.
I have 11 Volts at the Mini Relay #35 for the fuel pump and the relay tests out ok.
* I also have no spark.
* The battery is fully charged.
Here is a list of code I keep seeing besides the scrolling "Reduce Engine Power", "Service Traction System", "Brake before Shifting" and "Service ABS". Here are the other codes I'm getting.
C1276
C1255H
U1064H
PCM- 0601
1518 - (This will not clear)
1276
0601
1518.


Previous POSTING
I need some help with a C5 not starting. The vehicle has 10,000 miles on it. I started it about 3 weeks ago letting the engine run for a good 20 minutes. I gunned the engine and turn off the key. The engine shut off just fine. I then attempted to immediatly start it again only it wouldn't start.
It seems to continue to cycle through several error messages -Reduce Engine speed, Brake to shift, etc.
Anyone have any ideas what is happing here?

AC54ME

ttt - I cannot help, but one or more of the Forum members will chime in with assistance.

c5BlackBeauty

Try also posting in the Tech section. You may get some help over there in addition to what folks may come back with here. GOod luck,

Corpsvette

PM Bill Curlee or Patches, they will know!!!!!!!!!

JIm kay

Avanti

Though you say the battery is "charged," do you know if it is really any good? Have you checked the volts at the battery? 11 is too low there; I don't know about at any specific relay. Have you cleaned the cable-ends, relevant grounds, etc.? These things are gosh awful persnickety regarding battery condition... and the symptoms, as they say, may vary.

All the best.

runamuk

Are you saying that you can hit the "reset" button and all of the codes will go away with the exception of the P1518?

I'll look later on when I get home.

1253C5

Yes, I can clear all code accept the 1518 code. However, once I let the car set for a few seconds or cycle the ignition all the codes come back as I listed above. But they then can be cleared, just not the one code I mentioned.
The battery I have been told is good
According to my sheet of codes - P1518 indicates: PCM to TAC Module serial data circuit. But what's that?

This is driving me crazy...

realjedi

hey runamuk, unfortunately the only thing I can tell you is that you may have a defective computer chip. I have never seen this happen to a vette but have seen it happen to a camaro and a ford. On the ford the chip would work fine sometimes than go nuts other times. Have you taken it to a dealer? perhapse chevy, if you compliane enough, will help you replace it.

1253C5

No, I'm trying to avoid the dealier as I'm a little concerned about thier abilities (past experence). But I am at the point where I don't feel I have much choice.

1253C5

No I haven't taken it to the dealier, I'm trying like H@ll to avild them as I'm concerned about thier work (past experience). But it seems I have no other option at this point.

Bill Curlee

REPLACE YOUR TAC MODULE!!! If you have a continuous PCM P-1518, the TAC module is defective. You can check the Under Hood Electrical Center fuse# 17. That is power to the TAC module. This is IMPORTANT! The ground for the TAC mosule is G-106. It is on the engine block down near the rear of the starter motor. Examine that ground and clean it.

If all of this fails to correct the 1518 DTC replace the TAC module.

Please let me know if you have any other questions.

Bill Curlee

BlueDragon

Hum,
I still think battery and here is why. You are showing a bunch of codes. Don't forget your battery can measure good with a voltmeter and still not have enough Cranking amps and it pulls the system down when you try to crank. I would either pull the battery and take it to get tested or get a new battery before going and fussing with the modules. Check all FUSES and wires as stated below. The Circuit Description for the P1518 which will not clear is as follows:

The TAC Module and the 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.

Conditions for runnning the DTC
Ignition switch is in the crank or run position
The ignition voltage is greater than 5.23 volts (note this is not battery volts, this is measured at the ignition)

Conditions for setting the DTC
Invalid or missing serial data messages are detected for a predetermined amount of time.
All of the above conditions met for less than 1 sec.

Important:

DTC P1518 sets if the battery voltage is low. If the customers concern is slow cranking or no crank because battery voltage is low ignore DTC P1518. Clear any DTCs from memory that may have set from the low battery voltage condition. This means you have a bunch of other DTCs.

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 (i.e. cruise, brake). An inspection of the fuses may lead you to the circuit that is shorted to the TAC module ground circuit.

0Tony Mamo @ AFR

Check for fuel pressure at the schrader valve on the end of the drivers side fuel rail. You should actually hook a guage to it and make sure it reads 45-50 lbs. or so. If you don't have a guage at least depress the valve and you should see fuel should spray out at high pressure.

After that check the condition of the plugs....see if they are wet with fuel or anything else indicating you might have an issue with spark.

Good luck...check the fuel pressure right away...you might have a blown fuse, bad relay, or a bad pump.

Tony M.

PS If the car seems to be cranking over at normal speed, I would doubt its related to the battery...If the battery has enough grunt to crank the motor normally, it should easily have enough to "lite" the coilpacks providing spark for ignition.

Richin Chicago

Here is a diagram:

1253C5

Thanks All for the information - - I did replace the battery as of today as I checked it I felt it was dropping to low under load.
No change.
Bill, I will need some help locating the grounds your talking about.

Thanks again, keep it coming I will update everyone as I try your suggestions.

Rod

Coc5

I just had a similar problem with mine also. I even jumpered around the fuel pump relay to force the pump to run. It did run but made strange noises and my parking lights would dim. The parking lights going crazy told me I had a ground issue. It was the ground wire behind the drivers side rear wheel were it grounds under a nut on the side of the frame.

1253C5

I don't own a fuel pressure gage but to be down and dirty, I did press the valve on the fuel rail and I do have pressure there.
Do not know how much, but there is pressure there.

Can someone tell me where the TEC and the PCM modules are located?
I contacted the dealier they said that the PCM is located next to the battery, unfortunitly, I don't see it anywhere near the battery based on the information they provided.

chriskaw7r

runamuk

The PCM is under the battery, if you look behind the right front wheel you will see an access panel in the wheel well, if you remove this panel you'll see the PCM and the TAC module.

1253C5

We are talking about the location as being in the engine compartment, behind the right front wheel, correct?