My prelude died as I tried to pass a school bus. As embarrasing as that was, my ECU is throwing a constant CEL. I am not able to jump it to see what codes are coming up. It stays constant even when I jump it. I know I may need a new ECU? Could it be something else? No warning signs before it died!

 

i would try to get it on a snap[ on scanner or motis and see if there is communication. if not, time for diagnosage ie wiring, pin voltages, continuity checks etc.

 

Is that possible with a OBD2A ECU?

 

I think the helms discusses what it means if the cel is solid. What does it say?

 

As far as I know it means a dead ecu!

 

Then you find someone to swap with and test.

 

yes it is possible to check what i said above, and no you can not use my ecu to "test" with. anyone that would let you "borrow" an ecu, especially a honda ecu which don't f up often is nuts. there <U></U>could<U></U> be more issues than just ecu, and it would be risky for someone to do so. but if you find someone, then bob is an uncle of yours my friend, not mine

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by REDLUDE4WS &raquo;</TD></TR><TR><TD CLASS="quote">yes it is possible to check what i said above, and no you can not use my ecu to "test" with. anyone that would let you "borrow" an ecu, especially a honda ecu which don't f up often is nuts. there <U></U>could<U></U> be more issues than just ecu, and it would be risky for someone to do so. but if you find someone, then bob is an uncle of yours my friend, not mine </TD></TR></TABLE>

Why would I ask to use yours? I don't know you. You are not helping

 

a solid cel is something with the ecu. does the car run?
check all connections to the ecu and make sure pins are ok.

you can not borrow someones ecu if youre running obd2 preludes immobilizer system wont let you since the ecu is programmed for the key that the car uses. the key sends a signal to the immobilizer which sends it to the ecu which then sends it back to the immobilizer.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by BlacktraxGirl &raquo;</TD></TR><TR><TD CLASS="quote">a solid cel is something with the ecu. does the car run?
check all connections to the ecu and make sure pins are ok.

you can not borrow someones ecu if youre running obd2 preludes immobilizer system wont let you since the ecu is programmed for the key that the car uses. the key sends a signal to the immobilizer which sends it to the ecu which then sends it back to the immobilizer. </TD></TR></TABLE>

this is true, but IIRC if the chip is near the ignition it will read the same.
example:
your key to turn the ignition
the key of your friend whom you borrowed the ECU from right next to the ignition.

im pretty sure that will work

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by BlacktraxGirl &raquo;</TD></TR><TR><TD CLASS="quote">a solid cel is something with the ecu. does the car run?
check all connections to the ecu and make sure pins are ok.

you can not borrow someones ecu if youre running obd2 preludes immobilizer system wont let you since the ecu is programmed for the key that the car uses. the key sends a signal to the immobilizer which sends it to the ecu which then sends it back to the immobilizer. </TD></TR></TABLE>
The car will not start, and as soon as I jump it! It goes solid. I just purchased a new OBD2A ecu of ebay! Did I just waste my money?

 

yeah, seems so cuz of the immobilizer.. u can get it rekey'd to your car but thats more money.. how much did you pay for it?

 

$70.00. How can I get it rekeyed? The manual says just replace old ecu. The funny thing is that the CEL is not solid until I jump it. The manual says ECU failure.

 

Your reading the manuel wrong. If while the car is in the on postion you dont get a code and then you jump the harness and its a solid CEL it means no codes r stored.

Now if you go 2 jump the harness and there is no CEL light that means the ECU is dead.

You can also pull your ecu and look inside the ecu for burns or scortches.

Does your car crank? Have you tried anything else besides thinking its the ecu?

 

wait u r obd2. idk if those rules apply 2 u

 

I am running a hybrid setup. H22A in a OBD2A Prelude. I was told that a solid CEL when jump it, it means that the ecu is okay. I am going to check the Dizzy!

 

so it's not the ECU, fuel or Dizzy. What else could it be? Someone mention the PGM-FI main relay? Anyone have one?

 

Oh man, I hate to be the one to tell you this, but if your getting fuel and spark and there is still no combustion, well youve either got a blown motor or messed up timing.

Compression check will confirm ill compression

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Acidcrakker &raquo;</TD></TR><TR><TD CLASS="quote">Oh man, I hate to be the one to tell you this, but if your getting fuel and spark and there is still no combustion, well youve either got a blown motor or messed up timing.

Compression check will confirm ill compression</TD></TR></TABLE>

I have not checked for spark! I replaced the ignition coil and nothing change. Blown motor? How can that be? What about the main relay?

 

Well confirm the simple first.

Look for fuel and spark.

Do you know how to test those two?

 

Yes! I am getting fuel, but I figured just replacing the coil would let me know if that is the problem. How would I know if the timing belt broke? Also how do I do a compression test?

 

Well just replacing the coil isnt sufficent. The coil may have been fine, your rotar in the dizzy might have broken.

Go have someone crank the car over, take the spark plug wire out and stick it to a ground and look for a spark. Do that, and if there is spark, I will assist you further.

 

It's to late now, so I will let you know tomorrow. Thanks for your help!

 

On a obd2 how do you "Jump" it to check the cel. I know how to on a obd1. which pins in the obd2 connector or is his car obd1??? His sig. says 97 which is obd2? or did i just miss something???

 

I am running a OBD2A, with a OBD1 JDM H22A. So my Crank position sensor has been run to my OBD1 distributor!