wheeljo2

Been intermittent for a few months now on my 99 FRC, starter turns over but no power to fuel pumps, removed BCM and inspected but do not know if that may be the issue or not? Any ideas?

BLOWNBLUEZ06

Are you measuring for voltage at the wiring in back at the pump or just listening for the noise of the pump?

lucky131969

Not sure why you are removing the BCM. The PCM controls the fuel pump relay, not the BCM.

As already asked, have you checked voltage back at the pump connector with a DMM? Ground? Check for voltage and ground at the fuel pump relay?

Fast one

Is there pressure at the fuel rail? I thought that the pump would only go on for three seconds after the key is turned to provide 55 psi for the injectors unless the engine started. If the fuel rail has pressure and the engine doesn't start it sounds like something other than the pump such as no spark or injector commands. Power to the pump can be monitored with a meter and if there is power but no psi with no start you can wire the pump to the battery then check the fuel pressure at the fuel rail.

AVEYARDK

Any one know what pin turns on or off fuel. Vats bypass needs this wire. Pcm or bcm...either vats control will work. Bcm tells pcm that the vats code is ok, so i need either

lucky131969

What do you mean by "pin"? The fuel pump is controlled by the PCM, and has nothing to do with the BCM or VATS. If the code is not satisfied, and the correct code sent to the PCM via the BCM, then the PCM disables the fuel injectors.

The PCM controls the fuel pump relay by providing 12 volts. The relay is in turn grounded at SP122, which receives it's ground from G105 on the lower left side of the block.

AVEYARDK

Sorry, you are correct. I am looking for the location and wire to hook up bypass that will allow injectors to work.

lucky131969

Do a search, there are a few well documented threads on this. also check the stickys above.

AVEYARDK

3. Where is the VATS pin on my PCM, how do I find it:
The VATS signal wire will be labeled (in your vehicles service manual) as VATS, Fuel enable wire or circuit
number 229 and is normally a dark blue wire. The pin number at the PCM varies depending on application:
TBI/TPI 89-92 -------- pin# B6 (might be a white wire instead of dark blue)
TBI/TPI 91-92--------- pin# F10 of the ECM's 32pin E-F connector.
LT1 92-93 ------------- pin# 19 ("A19") of the PCM's 32 pin red connector
LT1 94-97 ------------- pin# 25 ("A25") of the PCM's 32 pin red connector
LS1 1998 -------------- pin# 11 of the PCM's 80 pin red connector
LS1 99-02 ------------- pin# 30 of the PCM's 80 pin red connector
3.8L V6 95-97 -------- pin# 55 of the blue PCM connector
3.4L DOHC V6 95 ---pin# A14
PCM# 16187424 -----pin D6 of the PCM's C3 connector
The VATS/Fuel enable wire can also be found on the BCM’s 10 pin blue connector, #230, position 'E' . In older
vehicles you will find the VATS wire on the PASSkeyII/VATS decoder module

I HAVE NO WIRE AT PCM LOCATION #30 RED CONNECTOR
NO 10 PIN BLUE CONNECTOR AT BCM
NO IDEA WHERE CIRCUT # 230 IS AT.

ANY HELP WOULD BE VERY THANKFUL

Bill Curlee

`You have NOT read and or posted your DTCs. Also need to know the status of the security light.

Please read and post the DTCs. If there are tons of History codes,,,clear them all and then try to start the car and see what comes back.

READING YOUR Engine Diagnostic Codes



The Diagnostic Display Mode is entered with the following procedure:
1) Turn on the ignition but don't start the engine.
2) Press the RESET button to turn off any warning messages. (i.e. door open, trunk open ect)
3) Press and hold OPTIONS
4) While holding OPTIONS, press FUEL four times within a 10-second period.


Initially, on-board diagnostics go into an Automatic Mode which shows diagnostic codes in a pre-set sequence: PCM - TCS - RTD - BCM - IPC - RADIO - HVAC - LDCM - RDCM - SCM - RFA. All codes will be displayed for each. ( i.e. PCM = 4 codes) If none are present in a given module, you will see No More Codes on the display.
There are two kinds of diagnostic codes, Current and History designated with a letter suffix, “C” or “H”. A current C code indicates a malfunction is present and active in the module displaying data. A history code indicates a problem existed sometime in the last 40 or 50 ignition cycles. When not accompanied by a current code of the same number, it's potential evidence of a previous problem, now resolved, that was not removed by clearing the codes.
More likely it's an indication of an intermittent malfunction.
Intermittent codes are the most challenging of the diagnostics. An intermittent code may have happened once, may have happened more than once but is inconsistent or may be happening on a regular basis but not at the time the codes are displayed. History codes can also be caused by a current malfunction in a system that is not operating at the time codes are displayed. An example is the rear window defogger which doesn't operate until the Body Control Module detects engine rpm. For history codes set by a module that does not operate with the key on and engine off, a special diagnostic tool called a Scan Tester is necessary to properly diagnose the malfunction.
Once the system has displayed all modules, it goes into the manual mode which allows selection of each module using combinations of Driver Information Center buttons. Manual mode can also be entered during the automatic sequence by pressing any button except English/Metric (E/M). Once the display shows Manual Diagnostics, select a module by pressing the OPTIONS button to go forward or the TRIP button to go back. Once a module is selected, a code is displayed, and if more than one are present; press GAGES to go forward or FUEL to go back.
To exit the diagnostic mode at any time, press E/M. If you want to erase codes in a given module, press and hold the RESET button To reset the codes once in manual mode, press and hold RESET until it displays NO CODES Press OPTIONS to go to the next module. Repeat the steps until you have reset the codes in all the computer modules.
NOTE!! Only reset the codes IF you want to - it is NOT necessary to do this. Clearing a code does not repair a problem. You are simply erasing the evidence of it in the module's memory. If you clear the code/s, and extinguish the Check Engine Light, your emissions status ready will NOT allow you to pass an emissions test until you have completed the required driving cycles.
Once you have the codes, the next question is: What to do with the information?
First, consult the factory service manual. Any serious C5 Do-It-Yourself owner should invest in the Corvette Service Manual of the appropriate model year. The Service Manual is really a requirement if you want to understand and work on your C5. You can GOOGLE the DTC and also find information on it.




Here is very good site that explains the DTCs:


http://www.corvette-web-central.com/C5DTCcode.html


http://www.obd-codes.com/trouble_cod...d-ii-codes.php



Make sure to include the H or C suffix!!




BC

wheeljo2

dual pumps in tank are not cycling on for 3 seconds when key is turned on, no fuel pressure is being registered on my pod gauge inside the car, no volt-meter readings were taken but the A terminal on the wire connector fires my test light when the key cycles on, never heard the bcm cycling on an off before (clicking noise like a relay) when the key is inserted all the way in the ignition switch and back out a half inch or so - could be normal operation but would like to know so I can rule out this as a viable culprit.

i have two dedicated relays mounted near the LR fuel tank with dedicated hots from the battery positive and two dedicated grounds off the frame and using the stock PCM wire from the underhood fuse box relay to trigger and send voltage to the stock GM wire connector on the outside of the stock fuel sending unit. I'm speculating that perhaps my pcm is not providing a strong enough voltage signal to fire the pumps because I have run a direct ground and hot lead from a battery charger directly to the two male pins that fire the pumps as a test case and they fire right up every time.

Fuel pump fuse and relay underhood check out fine. I'm thinking I need to run a new a signal wire with a heavier gauge from front to back or perhaps just incorporate a new heavy gauge wire from the ignition switch but do not know if that will interfere with any other PCM functions. Also, is there something in the VAT system that would disable the fuel delivery and if so is that tied to the BCM somehow? I inspected the BCM front and back of the circuit board and it appears to be good (no burnt spots anywhere). i'll put it back in and run the codes but nothing has ever registered when it has done it before and I can usually disconnect and reconnect the fuel connector on fuel sending unit and I can get it to start eventually and it generally stays running when it does start (did die on me one time at a traffic light idling but that was before I installed the two relays at the rear).