Code 51 PCM comm? Died on bridge? Weird!
Thread Starter
Drifting
Joined: Nov 1999
Posts: 1,502
Likes: 12
From: Yorktown Heights NY
Code 51 PCM comm? Died on bridge? Weird!
95 died this morning, also dtc 51, won't start
My 95 died on the Triboro bridge this morning....flat bedded it home. Would first crank and nearly run 2 seconds, now now only cranks.
Read codes all H as follows:32, 34, 36, 38, 51 and 85.
I have the service manuals and I looked up all the codes. Distributor was changed only two years ago.
Tried changing out the ignition module but that didn't fix it.
The thing stumbled a little on the way home on the parkway last night also and has stumbled after starting the past couple of weeks.
The code 51 has me concerned as I have lt1 edit and last month while reading the ECM the program said it was 100% complete but after I disconnected the fans stayed on when key was turned on and only way I got the car to turn back on was to remove the battery cable.
I now also get a checksum error when using pcmcom and cannot erase the above history codes.
Is ECM fried? Can I reload a good program back in with pcmcom to fix it?
Could this be causing my no start issue also?
My 95 died on the Triboro bridge this morning....flat bedded it home. Would first crank and nearly run 2 seconds, now now only cranks.
Read codes all H as follows:32, 34, 36, 38, 51 and 85.
I have the service manuals and I looked up all the codes. Distributor was changed only two years ago.
Tried changing out the ignition module but that didn't fix it.
The thing stumbled a little on the way home on the parkway last night also and has stumbled after starting the past couple of weeks.
The code 51 has me concerned as I have lt1 edit and last month while reading the ECM the program said it was 100% complete but after I disconnected the fans stayed on when key was turned on and only way I got the car to turn back on was to remove the battery cable.
I now also get a checksum error when using pcmcom and cannot erase the above history codes.
Is ECM fried? Can I reload a good program back in with pcmcom to fix it?
Could this be causing my no start issue also?
Melting Slicks
Joined: Aug 1999
Posts: 2,240
Likes: 41
From: Baltimore, MD USA
Some of the DTC's could be old ones and some DTC's are always listed as history.
51 could definitely keep the engine from starting.
36 would indicate Optispark problem but the engine should still run.
Appears the EEprom chip that contains the engine calibration has a
bad memory location which is causing the check sum error.
You can try reflashing the PCM. If you can't reflash, only fix assuming the problem is in the EEprom (bad memory chip) is to have someone unsolder the memory chip from the circuit board. Install a socket and install a new memory chip with the basic program to allow you to reflash the PCM with the proper engine calibration.
This guy used to do it but if you scroll down to repair information he says he is out of the business and refers you to madz28.com. If you go to that site it appears he may be out of business but there is a contact phone number listed.
http://www.akmcables.com/
http://www.madz28.com
Probably easier to get a replacement PCM.
51 could definitely keep the engine from starting.
36 would indicate Optispark problem but the engine should still run.
Appears the EEprom chip that contains the engine calibration has a
bad memory location which is causing the check sum error.
You can try reflashing the PCM. If you can't reflash, only fix assuming the problem is in the EEprom (bad memory chip) is to have someone unsolder the memory chip from the circuit board. Install a socket and install a new memory chip with the basic program to allow you to reflash the PCM with the proper engine calibration.
This guy used to do it but if you scroll down to repair information he says he is out of the business and refers you to madz28.com. If you go to that site it appears he may be out of business but there is a contact phone number listed.
http://www.akmcables.com/
http://www.madz28.com
Probably easier to get a replacement PCM.
Last edited by Hooked on Vettes; Jan 26, 2013 at 11:16 AM.
Thread Starter
Drifting
Joined: Nov 1999
Posts: 1,502
Likes: 12
From: Yorktown Heights NY
So I checked injectors with noid light...they are pulsing!
Checked for spark at plugs....spark is ok!
Checked for fuel at Schraeder valve....none!
Checked for voltage at fuel pump connector, none!
ECM is cutting off fuel!
Checked for spark at plugs....spark is ok!
Checked for fuel at Schraeder valve....none!
Checked for voltage at fuel pump connector, none!
ECM is cutting off fuel!
Last edited by 95BLKVette; Jan 27, 2013 at 02:07 PM.
Thread Starter
Drifting
Joined: Nov 1999
Posts: 1,502
Likes: 12
From: Yorktown Heights NY
I found the relays under the passenger knee panel (they are all the same) so I swapped the right one for the horn relay and still no change.
Hot wired the G ADL connector ad still no fuel pump run.
Conclusion, pump is DOA, my fuel guage has not been showing the level correctly for the past 5 years so decided to go with a new complete sender/pump assembly from Rockauto.com
Will also be replacing my ECM.....
Melting Slicks
Joined: Aug 1999
Posts: 2,240
Likes: 41
From: Baltimore, MD USA
On a 95 you have a 16 pin Diag. connector pin numbers 1-16. No way to enable the pump thru that connector.
Find Fuse #14 (FP 1) it's a 10amp fuse.
Find Fuse #2 (FP 2) it's a 20amp fuse.
Both of them are located in the passenger side fuse block.
If you look at the picture of the fuse below, the arrows
point to the fuse test points. Take a piece of wire and
jumper either test point from Fuse#14 to either test
point on Fuse #2 or push the jumper wire into either socket
prong the fuses plug in to.
Fuse #2 is hot all the time so you're applying 12 volts
to Fuse #14. The fuel pump should run.
No need to turn the ignition key on.
Last edited by Hooked on Vettes; Jan 27, 2013 at 06:54 PM.
Thread Starter
Drifting
Joined: Nov 1999
Posts: 1,502
Likes: 12
From: Yorktown Heights NY
On a 95 you have a 16 pin Diag. connector pin numbers 1-16. No way to enable the pump thru that connector.
Find Fuse #14 (FP 1) it's a 10amp fuse.
Find Fuse #2 (FP 2) it's a 20amp fuse.
Both of them are located in the passenger side fuse block.
If you look at the picture of the fuse below, the arrows
point to the fuse test points. Take a piece of wire and
jumper either test point from Fuse#14 to either test
point on Fuse #2 or push the jumper wire into either socket
prong the fuses plug in to.
Fuse #2 is hot all the time so you're applying 12 volts
to Fuse #14. The fuel pump should run.
No need to turn the ignition key on.
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Thread Starter
Drifting
Joined: Nov 1999
Posts: 1,502
Likes: 12
From: Yorktown Heights NY
I used the lighter fuse as I don't have #2 and connected a jumper from it to #14 FP#1 and no pump run...it's fried 
Thanks again, sender assembly with pump is on it's way......
Thanks again, sender assembly with pump is on it's way......
Melting Slicks
Joined: Aug 1999
Posts: 2,240
Likes: 41
From: Baltimore, MD USA
located in the under hood distribution block #1.
The Fuse #2 is not used in the passenger side fuse block.
Hard to believe you have a bad PCM and a bad fuel pump
at the same time?
Last edited by Hooked on Vettes; Jan 27, 2013 at 10:35 PM.
Burning Brakes
Joined: Apr 2006
Posts: 1,218
Likes: 7
From: Burleson Texas
I must have checked the wrong wire at the fuel pump connector.
I found the relays under the passenger knee panel (they are all the same) so I swapped the right one for the horn relay and still no change.
Hot wired the G ADL connector ad still no fuel pump run.
Conclusion, pump is DOA, my fuel guage has not been showing the level correctly for the past 5 years so decided to go with a new complete sender/pump assembly from Rockauto.com
Will also be replacing my ECM.....
I found the relays under the passenger knee panel (they are all the same) so I swapped the right one for the horn relay and still no change.
Hot wired the G ADL connector ad still no fuel pump run.
Conclusion, pump is DOA, my fuel guage has not been showing the level correctly for the past 5 years so decided to go with a new complete sender/pump assembly from Rockauto.com
Will also be replacing my ECM.....
Check pin number 7 on the red connectorof your PCM, thats the fuel pump relay enable, dark green and white wire. I think its a 5v signal. if that is not getting 5v when you turn the key on, or its not getting 5v when cranking, you might have a problem with the ecm
Burning Brakes
Joined: Apr 2006
Posts: 1,218
Likes: 7
From: Burleson Texas
I think you are missing some steps here...
throwing parts at it will just cost you money. If thats how you like to fix problems, cool. But I like to fix the cause of the problem. So in light of my own interest...
Did you see if the fuel pump relay is being enabled when you go key on?
Did you see if 12v was actually coming out of the relay when enabled?
Did you verify 12v at the fuse panel on the fuel pump fuse?
Did you verify the fuel pump fuse is good?
Did you verify the correct pins on the fuel pump connector?
Did you test for 12v at the fuel pump?
Did you supply 12v to the fuel pump and see if it works?
Did you test the volume flow of the pump?
Is the fuel filter good?
Did you use a fuel pressure gauge on the schroder valve to verify correct fuel pressure?
throwing parts at it will just cost you money. If thats how you like to fix problems, cool. But I like to fix the cause of the problem. So in light of my own interest...
Did you see if the fuel pump relay is being enabled when you go key on?
Did you see if 12v was actually coming out of the relay when enabled?
Did you verify 12v at the fuse panel on the fuel pump fuse?
Did you verify the fuel pump fuse is good?
Did you verify the correct pins on the fuel pump connector?
Did you test for 12v at the fuel pump?
Did you supply 12v to the fuel pump and see if it works?
Did you test the volume flow of the pump?
Is the fuel filter good?
Did you use a fuel pressure gauge on the schroder valve to verify correct fuel pressure?
Thread Starter
Drifting
Joined: Nov 1999
Posts: 1,502
Likes: 12
From: Yorktown Heights NY
I think you are missing some steps here...
throwing parts at it will just cost you money. If thats how you like to fix problems, cool. But I like to fix the cause of the problem. So in light of my own interest...
Did you see if the fuel pump relay is being enabled when you go key on?
Did you see if 12v was actually coming out of the relay when enabled?
Did you verify 12v at the fuse panel on the fuel pump fuse?
Did you verify the fuel pump fuse is good?
Did you verify the correct pins on the fuel pump connector?
Did you test for 12v at the fuel pump?
Did you supply 12v to the fuel pump and see if it works?
Did you test the volume flow of the pump?
Is the fuel filter good?
Did you use a fuel pressure gauge on the schroder valve to verify correct fuel pressure?
throwing parts at it will just cost you money. If thats how you like to fix problems, cool. But I like to fix the cause of the problem. So in light of my own interest...
Did you see if the fuel pump relay is being enabled when you go key on?
Did you see if 12v was actually coming out of the relay when enabled?
Did you verify 12v at the fuse panel on the fuel pump fuse?
Did you verify the fuel pump fuse is good?
Did you verify the correct pins on the fuel pump connector?
Did you test for 12v at the fuel pump?
Did you supply 12v to the fuel pump and see if it works?
Did you test the volume flow of the pump?
Is the fuel filter good?
Did you use a fuel pressure gauge on the schroder valve to verify correct fuel pressure?
Checked for ground at fuel pump wire...yup.
Hot wired cigar lighter fuse to fp1 fuse....both fuses are good but pump did not run. this is a direct path to the pump.
