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View Full Version : What keeps resetting my 98 civic ecm when car is turned off


tllewis
Jul 22, 2010, 10:24 AM
Its been since April I can't pass emissions because after I turn the car off to start the test the codes clear every time. The car reads ready till its turned off then once back on it has cleared the rediness I have no trouble codes showing the car runs fine I've replaced thermostate, o2 sensor ,plugs wires and, battery cables I've checked all fuses someone please any answers??

Fr_Chuck
Jul 22, 2010, 07:36 PM
Moved to cars

TxGreaseMonkey
Jul 22, 2010, 08:28 PM
Attach a code reader to the Data Link Connector and check for codes. Clear any old codes, where repairs have been made, with the reader.

I'm confused since you don't want any codes to be stored in the ECM's memory, in order to pass inspection. It sounds like you want codes.

kitch428
Jul 23, 2010, 11:04 AM
Is there an OBDII fuse on Honda's? That would explain why monitors never set. He's losing ecm memory on this one.

TxGreaseMonkey
Jul 23, 2010, 12:02 PM
There's a 7.5A ECM Backup Fuse in the under hood fuse box. Kitch428, are you suggesting the fuse is loose and it's erasing codes and monitors? If so, he could remove the fuse, clean the contacts, slightly bend the tangs, and reinstall. I would also clean the main ECM ground, located on the thermostat housing, and apply dielectric grease. Should the problem persist, there's an internal problem with the ECM (highly likely).

kitch428
Jul 23, 2010, 03:42 PM
Yeah, that's what I was talking about. I've seen some fuses burnt (on our cars, OBD) from tampering or from faulty ECM's.
Hey, Lewis, is there any history on the car that you can give us as to what was done in the past?

tllewis
Jul 25, 2010, 11:14 AM
Sorry, I don't mean like troublecode are clearing its clearing where is says the car is ready to be tested it fails for readiness cause when they turn the car off to start the test all good info is cleared . Like it all reads fine I herd there was a fuse I've had it checked it was fine I've disconnected the negative bat cable for a bit to see if that would help I drove a little over 100 mile to try rest for the new parts I've put on that didn't work still failed . I have cleaned all the ground wires to the car. I know of the ground wire to the thermostate I'm not sure if that one was cleaned ill check also if a different screw than the original was put onto the thermostat will that mess with the ground to the computer ? I have not herd the history on the car the guy at the emission place ask me the samething I know that because the car was a repo that's where I got it someone cut the hose to the airfilter its still the same way its maybe 4-5 inc long I'm sure the car does not get good cool air intake could this cause a problem ? Also I just found a leak in the front part of the motor going to the raidiator kind of looks like a baby thermostate it leaks around where it connects together not sure what that part is the car has been running hot could all this tie together somehow ?

TxGreaseMonkey
Jul 25, 2010, 01:52 PM
Yea, check the main ECM ground. If the problem persists, then I suspect the ECM is bad.

kitch428
Jul 25, 2010, 02:22 PM
Sounds like ECM. The RAM (random access memory) is referred to as volatile memory.
Volatile memory requires constant power to maintain what's stored in it.
When the power is removed, the memory is erased.
You want to maintain that rediness but when you cycle the key off, you're losing that volatile memory.
RAM, of course, is part of the computer.

tllewis
Jul 25, 2010, 03:47 PM
So is the ram a replaceable part or is it the computer its self ? What you said about the ram an what happens when it looses power to it it clears out that's the problem I'm having the emissions place said it was like I'm disconnecting the battery every time the car is turned off sounds very similar to what's going on what should I do ? Is it something I can fix like a wire /cable or is it the whole computer I need to replace ? This is the closest information I have gotten to my problem thanks !what should I do next?

TxGreaseMonkey
Jul 25, 2010, 04:12 PM
Replace the ECM, if you are sure the ground is good:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-selected-other-vehicles-46563-3.html#post235038

It's not a difficult job. Look for a remanufactured ECM--shop price and warranty.

kitch428
Jul 25, 2010, 04:25 PM
Copy down your part number of the ecm and start looking. Unless you are fortunate to find a donor for testing.
Here's a place to start looking on the cheap, but any guarantee? Hmmm
98 Civic ECM items - Get great deals on eBay Motors items on eBay.com! (http://shop.ebay.com/?_from=R40&_trksid=p3907.m570.l1313&_nkw=98+Civic+ECM&_sacat=See-All-Categories)

TxGreaseMonkey
Jul 25, 2010, 04:28 PM
Yes, you want to remove the old ECM first and get an exact Honda Part No. match.