Allpar Forums banner
1 - 8 of 8 Posts

·
Registered
Joined
·
237 Posts
Discussion Starter · #1 ·
I own a still young '99 LHS with 435,000 on the clock and it tripped code P1496 out of the blue. Is the ECM trying to die or should I be looking somewhere else?
 

·
Registered
Joined
·
237 Posts
Discussion Starter · #2 ·
I should have added that I've since checked all the plugs going to the ECM and cleared the code and pulled the neg. terminal to clear the code. So far, it hasn't returned.
 

·
Super Moderator
1966 Crown Coupe, 2016 200 S AWD, 1962 Lark Daytona V8.
Joined
·
22,521 Posts
P1496 is a regulated 5 volt supply line (Vt/Wt wire) failure from the PCM to the sensors. You may need it to act up again in order to find it.
See attached for troubleshooting.

82269
 

Attachments

·
Registered
Joined
·
237 Posts
Discussion Starter · #4 ·
P1496 is a regulated 5 volt supply line (Vt/Wt wire) failure from the PCM to the sensors. You may need it to act up again in order to find it.
See attached for troubleshooting.

View attachment 82269
Thanks for the reply. I have been trying all day to get it to trip that code again with no luck. I did however find that I had placed a shop rag in the gap just above the PCM for checking the oil. When the code tripped it was a balmy 103° and had been parked for several minutes with the A/C running. The rag has since been relocated but, after 2.5 hrs of driving, no code. In some other postings, there was at least 1 other code with it. When it tripped yesterday, the only code was P1496.
 

·
Registered
Joined
·
237 Posts
Discussion Starter · #5 ·
Thanks for the reply. I have been trying all day to get it to trip that code again with no luck. I did however find that I had placed a shop rag in the gap just above the PCM for checking the oil. When the code tripped it was a balmy 103° and had been parked for several minutes with the A/C running. The rag has since been relocated but, after 2.5 hrs of driving, no code. In some other postings, there was at least 1 other code with it. When it tripped yesterday, the only code was P1496.
Drove it around yesterday for 3 hrs. No "luck"! Now I hope it survives a 1400 mile trip to Texas. Hoping it was just a fluke.
 

·
Registered
Joined
·
1,483 Posts
Since it only happened once, and only when you had it parked running for an extended period on a hot day with the AC on, perhaps the AC pressure switch has a short when the pressure gets too high? Just spitballing here. Could be any of those sensors listed. Essentially, one may be having an intermittent failure, but the only way to know is to be able to real-time test the sensor when it fails, which sounds like a tall order based on the extremely intermittent nature.

The other solution is to replace all of those sensors after thorough tracing of the wires in the harness themselves show no wear-through or shorting out on something.
 

·
Registered
Joined
·
237 Posts
Discussion Starter · #7 ·
Since it only happened once, and only when you had it parked running for an extended period on a hot day with the AC on, perhaps the AC pressure switch has a short when the pressure gets too high? Just spitballing here. Could be any of those sensors listed. Essentially, one may be having an intermittent failure, but the only way to know is to be able to real-time test the sensor when it fails, which sounds like a tall order based on the extremely intermittent nature.

The other solution is to replace all of those sensors after thorough tracing of the wires in the harness themselves show no wear-through or shorting out on something.
Believe it or not, with the old girls age and mileage all the harnesses look to be in good shape and the plugs going into the ecm are pretty much spotless. Taking a 1500 mile trip to Texas next week. I hope it hangs together. I'm still looking to get the ol' girl to 500,000 without tearing into it.
 

·
Registered
Joined
·
1,483 Posts
I don't know about you but I still redline mine frequently. If it dies, it's going to die the way it lived!
 
1 - 8 of 8 Posts
Top