Too many codes
Thread Starter
6th Gear
Joined: Nov 2013
Posts: 6
Likes: 0
From: pukalani hi
Too many codes
Aloha from Maui
This is my first time here asking for help. I have an 87 corvette convertible about a hundred thousand miles on her. No mods other than cat back exhaust. Started running bad on the way home from work a couple of months ago and the check engine light came on. I checked the codes when I got home and was surprised to find all these codes.
24, 34, 41, 42, 43, 44, 45, 46, 51, 51, 52, 54, 63
51 does come up twice I thought it was the computer or prom so I replaced both the computer and prom. Same codes no difference at all
took the car to a mechanic he tested all the wiring he said and told me to replace the egr valve and all codes would go away although I thought this was completely wrong I did it and surprise surprise nothing changed except the 200 dollars I paid for diagnostic services.
Anyway can anybody give me an idea of where to start looking for the problem or what the problem might be I would really appreciate it. At this point I am thinking dealer repair and can't even begin to guess the dealer cost for diagnostics.
thanks for any help
Kevin
This is my first time here asking for help. I have an 87 corvette convertible about a hundred thousand miles on her. No mods other than cat back exhaust. Started running bad on the way home from work a couple of months ago and the check engine light came on. I checked the codes when I got home and was surprised to find all these codes.
24, 34, 41, 42, 43, 44, 45, 46, 51, 51, 52, 54, 63
51 does come up twice I thought it was the computer or prom so I replaced both the computer and prom. Same codes no difference at all
took the car to a mechanic he tested all the wiring he said and told me to replace the egr valve and all codes would go away although I thought this was completely wrong I did it and surprise surprise nothing changed except the 200 dollars I paid for diagnostic services.
Anyway can anybody give me an idea of where to start looking for the problem or what the problem might be I would really appreciate it. At this point I am thinking dealer repair and can't even begin to guess the dealer cost for diagnostics.
thanks for any help
Kevin
Thread Starter
6th Gear
Joined: Nov 2013
Posts: 6
Likes: 0
From: pukalani hi
Running bad loss of power seeming like no spark advance, very poor throttle response with hesitation off idle through about 1800 rpm some missing runs very badly when cold backfire up through intake.
tune up was done when I replaced the computer. New cap, new coil, new ignition module, new wires, new plugs . and as with the computer replacement and the egr replacement there is no difference in either the performance or the codes.
Le Mans Master
Joined: Mar 2004
Posts: 5,107
Likes: 171
From: Dublin CA
Are you sure you purchased the correct ECM and PROM?? Most of these codes indicate you should check the connection to the ECM. My gut feel is that either your connectors (plugs) to the ECM are coroided and need cleaning or perhaps are not making a good contact. Or you were giver the incorrect ECM and PROM.
24 - Vehicle Speed sensor
34 - Mass Air Flow sensor circuit
41 - Cylinder select error (check connections at ECM)
42 - Electronic Spark Timing Circuit (check the wiring and connections between the ignition module and the ECM
43 - Knock Sensor circuit (Check the ECM or an open or short to ground)
44 -Lean exhaust (check the wiring and connectors from the oxygen sensor t the ECM
45 -Rich exhaust (check for sticking EGR valve)
46 - Vehicle Anit-Theft System circuit (check for open or short in circuit from the VATS module to the ECM
51 -PROM/EEPROM error (faulty or incorrect PROM/EEPROM.
52- Engine oil temperature circuit (check connection at the oil temperature switch
54 -Fuel pump circuit (low voltage) (check the fuel pump circuit for shorts or damage)
63 -Right bank oxygen sensor circuit (check wiring and connections from the oxygen sensor to ECM)
24 - Vehicle Speed sensor
34 - Mass Air Flow sensor circuit
41 - Cylinder select error (check connections at ECM)
42 - Electronic Spark Timing Circuit (check the wiring and connections between the ignition module and the ECM
43 - Knock Sensor circuit (Check the ECM or an open or short to ground)
44 -Lean exhaust (check the wiring and connectors from the oxygen sensor t the ECM
45 -Rich exhaust (check for sticking EGR valve)
46 - Vehicle Anit-Theft System circuit (check for open or short in circuit from the VATS module to the ECM
51 -PROM/EEPROM error (faulty or incorrect PROM/EEPROM.
52- Engine oil temperature circuit (check connection at the oil temperature switch
54 -Fuel pump circuit (low voltage) (check the fuel pump circuit for shorts or damage)
63 -Right bank oxygen sensor circuit (check wiring and connections from the oxygen sensor to ECM)
Thread Starter
6th Gear
Joined: Nov 2013
Posts: 6
Likes: 0
From: pukalani hi
Are you sure you purchased the correct ECM and PROM?? Most of these codes indicate you should check the connection to the ECM. My gut feel is that either your connectors (plugs) to the ECM are coroided and need cleaning or perhaps are not making a good contact. Or you were giver the incorrect ECM and PROM.
24 - Vehicle Speed sensor
34 - Mass Air Flow sensor circuit
41 - Cylinder select error (check connections at ECM)
42 - Electronic Spark Timing Circuit (check the wiring and connections between the ignition module and the ECM
43 - Knock Sensor circuit (Check the ECM or an open or short to ground)
44 -Lean exhaust (check the wiring and connectors from the oxygen sensor t the ECM
45 -Rich exhaust (check for sticking EGR valve)
46 - Vehicle Anit-Theft System circuit (check for open or short in circuit from the VATS module to the ECM
51 -PROM/EEPROM error (faulty or incorrect PROM/EEPROM.
52- Engine oil temperature circuit (check connection at the oil temperature switch
54 -Fuel pump circuit (low voltage) (check the fuel pump circuit for shorts or damage)
63 -Right bank oxygen sensor circuit (check wiring and connections from the oxygen sensor to ECM)
24 - Vehicle Speed sensor
34 - Mass Air Flow sensor circuit
41 - Cylinder select error (check connections at ECM)
42 - Electronic Spark Timing Circuit (check the wiring and connections between the ignition module and the ECM
43 - Knock Sensor circuit (Check the ECM or an open or short to ground)
44 -Lean exhaust (check the wiring and connectors from the oxygen sensor t the ECM
45 -Rich exhaust (check for sticking EGR valve)
46 - Vehicle Anit-Theft System circuit (check for open or short in circuit from the VATS module to the ECM
51 -PROM/EEPROM error (faulty or incorrect PROM/EEPROM.
52- Engine oil temperature circuit (check connection at the oil temperature switch
54 -Fuel pump circuit (low voltage) (check the fuel pump circuit for shorts or damage)
63 -Right bank oxygen sensor circuit (check wiring and connections from the oxygen sensor to ECM)
Although I got the prom off ebay it is said to have come from a running 87 vette with automatic transmission. I can interchange either ecm and prom and nothing changes. I have cleaned the plugs at the ecm and opened cleaned and reattached all wiring harness connections that I can find, both under the dash and in the engine compartment. I could try again buying a new ecm and prom but I don't want to throw any more money at it without some idea that it will help.
most of the codes seem to say wiring problem but I haven't found anything faulty
Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,216
From: Park City Utah
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
Usually if you get a zillion codes like that it's caused by a bad ECM ground. On your car that should be on the side of the block above the oil filter (where the negative battery cable attaches). It's possible that it's on a bellhousing bolt, but I don't think it was moved there until '88 or '89 (it definitely was there in '89). There should be about 5 or 6 small black wires there.
When you get a new EPROM or MEMCAL module, it should match your year, transmission type and rear axle ratio. The 3 or 4 letter BCC (BroadCast Code) on the silver label should be the same.
When you get a new EPROM or MEMCAL module, it should match your year, transmission type and rear axle ratio. The 3 or 4 letter BCC (BroadCast Code) on the silver label should be the same.
Last edited by Cliff Harris; Jan 10, 2014 at 03:03 AM.
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Le Mans Master
Joined: Feb 2005
Posts: 6,485
Likes: 566
From: Clearwater Florida
Usually if you get a zillion codes like that it's caused by a bad ECM ground. On your car that should be on the side of the block above the oil filter (where the negative battery cable attaches). It's possible that it's on a bellhousing bolt, but I don't think it was moved there until '88 or '89 (it definitely was there in '89). There should be about 5 or 6 small black wires there.
When you get a new EPROM or MEMCAL module, it should match your year, transmission type and rear axle ratio. The 3 or 4 letter BCC (BroadCast Code) on the silver label should be the same.
When you get a new EPROM or MEMCAL module, it should match your year, transmission type and rear axle ratio. The 3 or 4 letter BCC (BroadCast Code) on the silver label should be the same.
..... On the 87 the ground wires are on the drivers side of the block under a large bolt just above the oil filter ... easy enough to get at ... start there ... remove the bolt , clean all the contact points and wire ends and re-tighten ... it won't hurt to attach a grounding wire directly to the case of the ECM , take the other end to a verified ground ... verify with a test light ........
Last edited by C409; Jan 10, 2014 at 07:33 AM.
Melting Slicks
Joined: Nov 2007
Posts: 2,830
Likes: 147
From: Gainesville FL
41 - Cylinder select error (check connections at ECM)==)>PROM
Code 41 is likely the prom cone bad. Sometimes hard to come by and they are interchanged when you change your ECM. I had to use a hypertech because I couldn't source a stock one for my 1986 ... fixed code 41 and bad running.
Are you sure you purchased the correct ECM and PROM?? Most of these codes indicate you should check the connection to the ECM. My gut feel is that either your connectors (plugs) to the ECM are coroided and need cleaning or perhaps are not making a good contact. Or you were giver the incorrect ECM and PROM.
24 - Vehicle Speed sensor
34 - Mass Air Flow sensor circuit
41 - Cylinder select error (check connections at ECM)
42 - Electronic Spark Timing Circuit (check the wiring and connections between the ignition module and the ECM
43 - Knock Sensor circuit (Check the ECM or an open or short to ground)
44 -Lean exhaust (check the wiring and connectors from the oxygen sensor t the ECM
45 -Rich exhaust (check for sticking EGR valve)
46 - Vehicle Anit-Theft System circuit (check for open or short in circuit from the VATS module to the ECM
51 -PROM/EEPROM error (faulty or incorrect PROM/EEPROM.
52- Engine oil temperature circuit (check connection at the oil temperature switch
54 -Fuel pump circuit (low voltage) (check the fuel pump circuit for shorts or damage)
63 -Right bank oxygen sensor circuit (check wiring and connections from the oxygen sensor to ECM)
24 - Vehicle Speed sensor
34 - Mass Air Flow sensor circuit
41 - Cylinder select error (check connections at ECM)
42 - Electronic Spark Timing Circuit (check the wiring and connections between the ignition module and the ECM
43 - Knock Sensor circuit (Check the ECM or an open or short to ground)
44 -Lean exhaust (check the wiring and connectors from the oxygen sensor t the ECM
45 -Rich exhaust (check for sticking EGR valve)
46 - Vehicle Anit-Theft System circuit (check for open or short in circuit from the VATS module to the ECM
51 -PROM/EEPROM error (faulty or incorrect PROM/EEPROM.
52- Engine oil temperature circuit (check connection at the oil temperature switch
54 -Fuel pump circuit (low voltage) (check the fuel pump circuit for shorts or damage)
63 -Right bank oxygen sensor circuit (check wiring and connections from the oxygen sensor to ECM)
Thread Starter
6th Gear
Joined: Nov 2013
Posts: 6
Likes: 0
From: pukalani hi
I removed and cleaned the wires at the common ground I also grounded the ecm with a wire to an under dash ground. I was hopeful since I had not previously thought about either of these things but now sad because neither made any difference. the prom I purchased and installed is ABTD my original was ABTK the only difference is gearing so I think it should run properly except for shifting but I am now looking for a ABTK replacement prom. installing either prom gives me the same codes so I am still thinking it is not the prom but some wiring issue that I have not yet found.