Crank no start after heater core replacement
03-03-2018, 04:02 PM
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Crank no start after heater core replacement
Hello! I have a 2003 Honda Accord EX k24a4 5MT sedan.
I’m having this issue with my immobilizer (and possibly my ECU). I’ll give the story in detail, then list the symptoms. Here’s the story:
The car started overheating one very cold winter night so I turned it off. A few minutes later, I saw coolant had leaked on the passenger floor and realized the heater core needed to be replaced, so I repaired it myself over an 8-day period. Once everything was back up, I attempted to start the car with a now drained battery; decided to get a whole new battery to start it once more and was greeted by a constant flashing immobilizer key signal.
Left the car for about 24hrs, came back, tried again and it started fine and worked optimally for about 2 days. On the 3rd day, it was back to the immobilizer issue and has been that way for about 2-3 weeks (and counting) ever since.
Recently, I realized since coolant leaked from the heater core, I should take a look at the ECU itself...discovered coolant pouring from around the connector pin housing. Inside smelled like coolant
and there was what looked like a blue buildup, most likely semi-dried, but where the pins are situated was dry.
On the board itself, there were no signs of short-circuitry, or intense corrosion for that matter, just a yellow substance that appears to be adhesive of some sort or early corrosion (which really doesn’t seem to be the case.) I went over the entire board with 70% isopropyl alcohol and q-tips, then allowed it to evaporate and air dry. Reconnected everything, but it’s all still the same.
Here’s a list of the symptoms the car has:
• Crank, no start
• Constant, flashing immobilizer and low pressure oil indicators
• None of the OBD2 Diagnostic tools Ive tried can communicate with the ECU
• I’ve checked all fuses and rechecked all connectors.(Remember it did work fine for 2 days)
• Key Fob works as it should (locks, unlocks, etc)
Car is as stock as it was April 2003, has absolutely nothing aftermarket installed, no remote start, no foreign wiring, nothing.
Not going to tow to a stealership. It took hell just for them to give me the immobilizer bypass brake code even with proof of ownership.(This did not work for me by the way.)
All your advice, scheming, teasing, hazing and jokes are welcome! “pls help.
I’m having this issue with my immobilizer (and possibly my ECU). I’ll give the story in detail, then list the symptoms. Here’s the story:
The car started overheating one very cold winter night so I turned it off. A few minutes later, I saw coolant had leaked on the passenger floor and realized the heater core needed to be replaced, so I repaired it myself over an 8-day period. Once everything was back up, I attempted to start the car with a now drained battery; decided to get a whole new battery to start it once more and was greeted by a constant flashing immobilizer key signal.
Left the car for about 24hrs, came back, tried again and it started fine and worked optimally for about 2 days. On the 3rd day, it was back to the immobilizer issue and has been that way for about 2-3 weeks (and counting) ever since.
Recently, I realized since coolant leaked from the heater core, I should take a look at the ECU itself...discovered coolant pouring from around the connector pin housing. Inside smelled like coolant
and there was what looked like a blue buildup, most likely semi-dried, but where the pins are situated was dry.
On the board itself, there were no signs of short-circuitry, or intense corrosion for that matter, just a yellow substance that appears to be adhesive of some sort or early corrosion (which really doesn’t seem to be the case.) I went over the entire board with 70% isopropyl alcohol and q-tips, then allowed it to evaporate and air dry. Reconnected everything, but it’s all still the same.
Here’s a list of the symptoms the car has:
• Crank, no start
• Constant, flashing immobilizer and low pressure oil indicators
• None of the OBD2 Diagnostic tools Ive tried can communicate with the ECU
• I’ve checked all fuses and rechecked all connectors.(Remember it did work fine for 2 days)
• Key Fob works as it should (locks, unlocks, etc)
Car is as stock as it was April 2003, has absolutely nothing aftermarket installed, no remote start, no foreign wiring, nothing.
Not going to tow to a stealership. It took hell just for them to give me the immobilizer bypass brake code even with proof of ownership.(This did not work for me by the way.)
All your advice, scheming, teasing, hazing and jokes are welcome! “pls help.
03-05-2018, 07:47 AM
#2
Honda-Tech Member
Re: Crank no start after heater core replacement
Hello! I have a 2003 Honda Accord EX k24a4 5MT sedan.
I’m having this issue with my immobilizer (and possibly my ECU). I’ll give the story in detail, then list the symptoms. Here’s the story:
The car started overheating one very cold winter night so I turned it off. A few minutes later, I saw coolant had leaked on the passenger floor and realized the heater core needed to be replaced, so I repaired it myself over an 8-day period. Once everything was back up, I attempted to start the car with a now drained battery; decided to get a whole new battery to start it once more and was greeted by a constant flashing immobilizer key signal.
Left the car for about 24hrs, came back, tried again and it started fine and worked optimally for about 2 days. On the 3rd day, it was back to the immobilizer issue and has been that way for about 2-3 weeks (and counting) ever since.
Recently, I realized since coolant leaked from the heater core, I should take a look at the ECU itself...discovered coolant pouring from around the connector pin housing. Inside smelled like coolant
and there was what looked like a blue buildup, most likely semi-dried, but where the pins are situated was dry.
On the board itself, there were no signs of short-circuitry, or intense corrosion for that matter, just a yellow substance that appears to be adhesive of some sort or early corrosion (which really doesn’t seem to be the case.) I went over the entire board with 70% isopropyl alcohol and q-tips, then allowed it to evaporate and air dry. Reconnected everything, but it’s all still the same.
Here’s a list of the symptoms the car has:
• Crank, no start
• Constant, flashing immobilizer and low pressure oil indicators
• None of the OBD2 Diagnostic tools Ive tried can communicate with the ECU
• I’ve checked all fuses and rechecked all connectors.(Remember it did work fine for 2 days)
• Key Fob works as it should (locks, unlocks, etc)
Car is as stock as it was April 2003, has absolutely nothing aftermarket installed, no remote start, no foreign wiring, nothing.
Not going to tow to a stealership. It took hell just for them to give me the immobilizer bypass brake code even with proof of ownership.(This did not work for me by the way.)
All your advice, scheming, teasing, hazing and jokes are welcome! “pls help.
I’m having this issue with my immobilizer (and possibly my ECU). I’ll give the story in detail, then list the symptoms. Here’s the story:
The car started overheating one very cold winter night so I turned it off. A few minutes later, I saw coolant had leaked on the passenger floor and realized the heater core needed to be replaced, so I repaired it myself over an 8-day period. Once everything was back up, I attempted to start the car with a now drained battery; decided to get a whole new battery to start it once more and was greeted by a constant flashing immobilizer key signal.
Left the car for about 24hrs, came back, tried again and it started fine and worked optimally for about 2 days. On the 3rd day, it was back to the immobilizer issue and has been that way for about 2-3 weeks (and counting) ever since.
Recently, I realized since coolant leaked from the heater core, I should take a look at the ECU itself...discovered coolant pouring from around the connector pin housing. Inside smelled like coolant
and there was what looked like a blue buildup, most likely semi-dried, but where the pins are situated was dry.
On the board itself, there were no signs of short-circuitry, or intense corrosion for that matter, just a yellow substance that appears to be adhesive of some sort or early corrosion (which really doesn’t seem to be the case.) I went over the entire board with 70% isopropyl alcohol and q-tips, then allowed it to evaporate and air dry. Reconnected everything, but it’s all still the same.
Here’s a list of the symptoms the car has:
• Crank, no start
• Constant, flashing immobilizer and low pressure oil indicators
• None of the OBD2 Diagnostic tools Ive tried can communicate with the ECU
• I’ve checked all fuses and rechecked all connectors.(Remember it did work fine for 2 days)
• Key Fob works as it should (locks, unlocks, etc)
Car is as stock as it was April 2003, has absolutely nothing aftermarket installed, no remote start, no foreign wiring, nothing.
Not going to tow to a stealership. It took hell just for them to give me the immobilizer bypass brake code even with proof of ownership.(This did not work for me by the way.)
All your advice, scheming, teasing, hazing and jokes are welcome! “pls help.
If you posess the above,Ill try to help,otherwise you should find a qualified repair shop.
03-05-2018, 07:58 AM
#3
Honda-Tech Member
Re: Crank no start after heater core replacement
Just saw your other thread(why do you have two?)
Id be replacing that ECU based on the picture. That cannot be effectively cleaned. That build up is coolant,that means coolant made its way into the ECU. and was there during the hot and cold cycles.
The ECU is damaged.
Id be replacing that ECU based on the picture. That cannot be effectively cleaned. That build up is coolant,that means coolant made its way into the ECU. and was there during the hot and cold cycles.
The ECU is damaged.
03-06-2018, 05:17 AM
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Re: Crank no start after heater core replacement
Hello! Thanks for replying! My partner and I were posting on different forums and hadn't realized we'd both posted on the same one.
We had definitely come to that conclusion, but since there was no visible damage, we'd figured perhaps it can still be tested or salvaged. We own the service manual and used it to aid us in replacing the heater core, but when it comes to the "proper measuring tools" and "knowledge", I'd like to know more. Can you be more specific?
We had definitely come to that conclusion, but since there was no visible damage, we'd figured perhaps it can still be tested or salvaged. We own the service manual and used it to aid us in replacing the heater core, but when it comes to the "proper measuring tools" and "knowledge", I'd like to know more. Can you be more specific?
03-06-2018, 09:11 AM
#5
Honda-Tech Member
Re: Crank no start after heater core replacement
You will need a DMM, a 'scope, a Break Out Box, and a scan tool with enhanced data(NOT OBD 2 data) and the ability to set up and utilize these tools. You will also need the topography of the communications structure.(I dont believe that is in the SM, I believe you need an ETM) Modern repair shops and dealerships do not use paper manuals anymore,so Im not exactly sure where you would find that information outside of the 'net
Use the enhanced scan tool to try and communicate with ANY module, in order to establish a base. If there is NO communication at all, then use the DMM to measure the terminating resistors,(via the BOB) to see if the network has crashed. If it hasnt, then connect the scanner to the BOB and connect the scope to the proper DLC terminals and try communicating again while monitoring the voltage. Look for 3.5v high and 2.5v low, in the at rest position. Then look for oscillations while attempting to communicate.
Let me know what you have from there and we'll move forward........
........Or simply replace that obviously corroded ECU.
Use the enhanced scan tool to try and communicate with ANY module, in order to establish a base. If there is NO communication at all, then use the DMM to measure the terminating resistors,(via the BOB) to see if the network has crashed. If it hasnt, then connect the scanner to the BOB and connect the scope to the proper DLC terminals and try communicating again while monitoring the voltage. Look for 3.5v high and 2.5v low, in the at rest position. Then look for oscillations while attempting to communicate.
Let me know what you have from there and we'll move forward........
........Or simply replace that obviously corroded ECU.
03-07-2018, 10:47 AM
#7
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Re: Crank no start after heater core replacement
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03-07-2018, 11:48 AM
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Re: Crank no start after heater core replacement
If we're in luck, there may just be someone who's selling the ECU along with the key. Otherwise, we've got the reprogramming part covered. Thanks!
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