EFI Relay problem
06-30-21, 10:57 AM
#1
Pit Crew
Thread Starter
EFI Relay problem
Hi everyone, today I am stumped. I had posted a few days ago about a low B+ on the engine diagnostic connector and with help from the forum I solved the problem by switching the EFI relay with the horn relay. So far so good.
Now for the real problem. It seems that it is that relay (and ONLY that particular relay) will start the car. NO OTHER relay works! I have tried a new relay and a couple of older, but working, relays (same type, of course), and they do NOT start the car, but once I put it the relay that was the horn relay presto it starts right up.
BUT WAIT! It has developed yet another problem. It now has an extremely low idle - so much so that, when cold, it doesn't idle at all unless I give it some gas. Once it warms up a bit it would idle real smooth around 3-400 rpm and accelerate and basically run just fine.. Can anybody tell me what the heck may be going on? Are the two problems related? I don't think (but of course I don't know, that's why I'm here) that the PS idle up valve is causing it and I did clean out the IAC not too long ago.
Any help is greatly appreciated.
Now for the real problem. It seems that it is that relay (and ONLY that particular relay) will start the car. NO OTHER relay works! I have tried a new relay and a couple of older, but working, relays (same type, of course), and they do NOT start the car, but once I put it the relay that was the horn relay presto it starts right up.
BUT WAIT! It has developed yet another problem. It now has an extremely low idle - so much so that, when cold, it doesn't idle at all unless I give it some gas. Once it warms up a bit it would idle real smooth around 3-400 rpm and accelerate and basically run just fine.. Can anybody tell me what the heck may be going on? Are the two problems related? I don't think (but of course I don't know, that's why I'm here) that the PS idle up valve is causing it and I did clean out the IAC not too long ago.
Any help is greatly appreciated.
06-30-21, 02:13 PM
#2
what happens when you turn on the AC? the idle should raise.
how dirty was the IAC? did you pull the battery connection? i find that when i remove the battery it takes a few mins of driving for the ECU to recalibrate and hold the idle better.
low idle is a common problem on these cars so check other threads for insight.
also the next common issue are the ECU capacitors, and your JDM car is no exception:
https://www.clublexus.com/forums/ls-...capacitor.html
how dirty was the IAC? did you pull the battery connection? i find that when i remove the battery it takes a few mins of driving for the ECU to recalibrate and hold the idle better.
low idle is a common problem on these cars so check other threads for insight.
also the next common issue are the ECU capacitors, and your JDM car is no exception:
https://www.clublexus.com/forums/ls-...capacitor.html
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avhart (06-30-21)
06-30-21, 02:35 PM
#3
Pit Crew
Thread Starter
Hi Timmy, well my a/c is not working at the mo so that's a blank. The IAC was pretty bad but it was in the car since the beginning so that's no surprise and yes I did the battery thing. You didn't address that strange behavior of the EFI relay though. Everything started with that and we're talking just a couple days. It went like this:-
1. Car working fine
2. Car shut down after short run and then not starting
3. Low B+ voltage from diagnostic connector in engine bay
4. Switched EFI relay with horn relay
5. Car started right up and working fine
6. A couple days pass
7. Car still starting but with very low idle issue
8. Tried numerous other working relays in EFI port but none starting car except the one mentioned in #4 (is that strange or what?)
1. Car working fine
2. Car shut down after short run and then not starting
3. Low B+ voltage from diagnostic connector in engine bay
4. Switched EFI relay with horn relay
5. Car started right up and working fine
6. A couple days pass
7. Car still starting but with very low idle issue
8. Tried numerous other working relays in EFI port but none starting car except the one mentioned in #4 (is that strange or what?)
07-01-21, 09:48 AM
#4
Pit Crew
Thread Starter
Come on guys, can somebody else take a shot at this? Yodaone, Yamae, Timmy(again), Lex2K?
I won't mind one bit if you tell me you think that the relay issue means I have 4 defective relays, although they all test good. If you think so I will then look at the low idle problem as a separate issue that just managed to happen at the exact same time. I don't want to fool around with other stuff until I at least try and get the relay thing sorted out. Please go right ahead and tell me the relays are all defective, if that's what you think.
Thanks
I won't mind one bit if you tell me you think that the relay issue means I have 4 defective relays, although they all test good. If you think so I will then look at the low idle problem as a separate issue that just managed to happen at the exact same time. I don't want to fool around with other stuff until I at least try and get the relay thing sorted out. Please go right ahead and tell me the relays are all defective, if that's what you think.
Thanks
07-01-21, 10:03 AM
#5
i honestly don't think the relays are the problem. relays are a pretty simple device so it's likely a bigger issues...ECU capacitors! it's worth a shot to crack it open and inspect them.
from the thread:
from the thread:
SYMPTOMS:
Please understand that any one of these symptoms can be a sign of ECU capacitors beginning to fail. - You do not need all or most of them to have this issue!
Your ECU capacitors are strongly suspected if you have at least one of the following intermittent issues on your Lexus or Toyota:
● problems in getting into diagnostic mode or scanner says "no communication"
● random dropping into "limp home" mode
● weird shifting problems
● OBD port is unresponsive, seems dead
● throwing random fault codes
● engine won't rev out/rev limits at 2000 or less rpm
● engine runs like crap, then suddenly runs fine again
● random not starting or cutting out
● low idle or erratic idle
● often very hard to start, requires starting fluid
● transmission will not automatically shift, only manual shift is possible
● transmission jerks from 1st to 2nd gear, and kinda slips from 2nd to 3rd
● no A/C compressor operation
● idle speed rolling up and down, or sometimes too low and sometimes too high
● speedometer not working reliably
● speed (cruise) control not working
● tachometer not working sometimes
● air bag light flickering intermittently
● A/C going into reset with flashing front defog light (front defog light typically flashing 10 times)
● check engine light on sometimes, but no codes stored, often in concert with ECT light
● ECU not communicating with scanners or not displaying codes with jumper installed
● bad sulfur exhaust smell in concert with not running right above
Please understand that any one of these symptoms can be a sign of ECU capacitors beginning to fail. - You do not need all or most of them to have this issue!
Your ECU capacitors are strongly suspected if you have at least one of the following intermittent issues on your Lexus or Toyota:
● problems in getting into diagnostic mode or scanner says "no communication"
● random dropping into "limp home" mode
● weird shifting problems
● OBD port is unresponsive, seems dead
● throwing random fault codes
● engine won't rev out/rev limits at 2000 or less rpm
● engine runs like crap, then suddenly runs fine again
● random not starting or cutting out
● low idle or erratic idle
● often very hard to start, requires starting fluid
● transmission will not automatically shift, only manual shift is possible
● transmission jerks from 1st to 2nd gear, and kinda slips from 2nd to 3rd
● no A/C compressor operation
● idle speed rolling up and down, or sometimes too low and sometimes too high
● speedometer not working reliably
● speed (cruise) control not working
● tachometer not working sometimes
● air bag light flickering intermittently
● A/C going into reset with flashing front defog light (front defog light typically flashing 10 times)
● check engine light on sometimes, but no codes stored, often in concert with ECT light
● ECU not communicating with scanners or not displaying codes with jumper installed
● bad sulfur exhaust smell in concert with not running right above
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avhart (07-01-21)
07-01-21, 10:45 AM
#6
Pit Crew
Thread Starter
I got that Timmy and I must admit the ECU crossed my mind. I have another one that is not too healthy but I'm going to go ahead and try it and see what happens. I'll post again as soon as I have something.
Thank you for your interest and responses they are much appreciated.
Anthony
Thank you for your interest and responses they are much appreciated.
Anthony
07-01-21, 11:37 AM
#7
Lexus Fanatic
Are these relays you are swapping in/out exactly the same part number?
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avhart (07-01-21)
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07-01-21, 11:44 AM
#8
Hi Timmy, well my a/c is not working at the mo so that's a blank. The IAC was pretty bad but it was in the car since the beginning so that's no surprise and yes I did the battery thing. You didn't address that strange behavior of the EFI relay though. Everything started with that and we're talking just a couple days. It went like this:-
1. Car working fine
2. Car shut down after short run and then not starting
3. Low B+ voltage from diagnostic connector in engine bay
4. Switched EFI relay with horn relay
5. Car started right up and working fine
6. A couple days pass
7. Car still starting but with very low idle issue
8. Tried numerous other working relays in EFI port but none starting car except the one mentioned in #4 (is that strange or what?)
1. Car working fine
2. Car shut down after short run and then not starting
3. Low B+ voltage from diagnostic connector in engine bay
4. Switched EFI relay with horn relay
5. Car started right up and working fine
6. A couple days pass
7. Car still starting but with very low idle issue
8. Tried numerous other working relays in EFI port but none starting car except the one mentioned in #4 (is that strange or what?)
If after that AC clutch does not engage, most likely a bad mag clutch, but check connector & fuse.
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avhart (07-01-21)
07-01-21, 11:48 AM
#9
Some mention of low +B on some wires.
low +B is a local wire issue if +B everywhere else is ok.
Is +B an issue everywhere? If so the issue could be a batt or alternator. A bad alternator could drag batt V down and eventually kills the batt. With a well charged batt, does the +B issue seem to go away if you disconnect alternator fuse and you just run from the batt during the test.
low +B is a local wire issue if +B everywhere else is ok.
Is +B an issue everywhere? If so the issue could be a batt or alternator. A bad alternator could drag batt V down and eventually kills the batt. With a well charged batt, does the +B issue seem to go away if you disconnect alternator fuse and you just run from the batt during the test.
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avhart (07-01-21)
07-01-21, 12:54 PM
#10
Pit Crew
Thread Starter
Yes LeX2K, exactly the same. It may be the ECU but the fact that only this one relay actually does work to start the car is very puzzling. There is something else I failed to mention. Every relay other than that one gives a B+ voltage on the diagnostic connector of around 0.35 volts. This one relay that works gives the correct 12 volts.
07-01-21, 12:57 PM
#11
Pit Crew
Thread Starter
Not in my case unfortunately. My a/c compressor is kaput. I am in the process of getting the money to change it out. Thanks for the comment though. Its something to keep in mind. I appreciate it.
07-01-21, 01:00 PM
#12
Pit Crew
Thread Starter
The car has no other B+ issues. Its only low in the engine bay diag connector when I plug in any of the other spare relays I have. Then the car doesn't start - of course.
07-01-21, 08:35 PM
#13
Moderator
Is the fuel pump working at around 8V or so after the engine is started up? Lower than 5.5V is not enough in my experience. What will be happening if the resistor is bypassed or short-circuited? As a car aged, the fuel pump resistor tends to increase the resistance due to the oxidization of the surface of metal resistor element and the actual current path is narrowed down or becomes thinner.
Other than that, I would check voltage drops of related lines. The important thing is that the one side of the voltage meter is connected the +B line of the alternator and the other side each lines to the ECU, injectors, ignition coils or fuel pump relay. The reason why to connect the +B line of the alternator is to know the over all voltage drops of the connecting points including fuses and relays.
Other than that, I would check voltage drops of related lines. The important thing is that the one side of the voltage meter is connected the +B line of the alternator and the other side each lines to the ECU, injectors, ignition coils or fuel pump relay. The reason why to connect the +B line of the alternator is to know the over all voltage drops of the connecting points including fuses and relays.
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avhart (07-02-21)
07-02-21, 09:26 AM
#14
Pit Crew
Thread Starter
Hi again Yamae, thanks for your input. I am going to trouble shoot the voltages as you suggested and will post the results when I have an answer. Thank you for your comments.
Anthony
Anthony
07-16-21, 10:10 AM
#15
Pit Crew
Thread Starter
Right, This is specially for Timmy, Yamae, LeX2K and others, of course.
1. Problem: very low B+ voltage from Engine Diagnostic connector therefore fuel pump not coming on. Car not starting
2. Lots of troubleshooting validated Timmy's earlier post that it probably was NOT the EFI relay.
3. Here's what I just did - I jumpered Te1 and E1 in the connector to check my engine ECU codes - NO codes, indicating the ECU was ok
4. Removed jumper and using meter found B+ was now back to 12v in the Diagnostic connector.
5, Car started and ran fine.
Can anybody figure that out? Why should by just setting a jumper (then removing it) to check the ECU cause the B+ to come back?
1. Problem: very low B+ voltage from Engine Diagnostic connector therefore fuel pump not coming on. Car not starting
2. Lots of troubleshooting validated Timmy's earlier post that it probably was NOT the EFI relay.
3. Here's what I just did - I jumpered Te1 and E1 in the connector to check my engine ECU codes - NO codes, indicating the ECU was ok
4. Removed jumper and using meter found B+ was now back to 12v in the Diagnostic connector.
5, Car started and ran fine.
Can anybody figure that out? Why should by just setting a jumper (then removing it) to check the ECU cause the B+ to come back?
Last edited by avhart; 07-16-21 at 10:16 AM.