1. Home
  2. Home Repair
  3. limp-in mode
  4. Page 2

limp-in mode

I think you're in limp-wristed mode.

Reply to
trader_4
Loading thread data ...

That is supposed to throw a code but I suppose it might pass the test and still be bad.

Reply to
gfretwell

"Clare Snyder"

Please re-read this, Clare, and clarify this. It sounds 'fishy' to me... phil

Reply to
Phil Kangas

The way I take it seems correct.

  1. Disconnect the ground (usually negative) wire from the battery. This is the correct way to start taking a battery out.

  1. Take this wire and touch it to the positive battery post ( again assuming a negative ground system).

That last step helps to discharge any capacitors in the system that may keep the computer active or holding a memory.

He is simply following the standard battery replacement where you disconnect the ground wire first , then the positive. This helps to prevent welding the wrench from the battery to the frame of the car if you do it in reverse and start with the positive lead.

If starting with the positive battery lead and the wrench makes contact with the frame of the car and the negative lead is still hooked up, you get major fireworks. If you start with the ground lead, it does not make any difference if the wrench touches an already grounded frame. There may be some very low level current that can flow due to all the electronics , but not very much.

Reply to
Ralph Mowery

How? You ALWAYS disconnect the ground first, right? So you take the ground cable and short it to the power cable - which has NO voltage on it measured to the chassis ground except a possible memory charge in the ECU. Shorting them helps drain the memory to reset the CEL. Exactly the same as removing the power wire and grounding it but daves one step - as you ALWAYS remove the ground first and connect the ground last - RIGHT???? By the vehicle end I mean the cable coming FROM the vehicle ground to the battery - just to be sure some dimbulb doesn't disconnect the ground cable from the engine or chassis instead of from the battery, then connect that (still connected to the battery - end) to the positive!

Reply to
Clare Snyder

"Clare Snyder" >

1."The VEHICLE end of the ground cable to the positive cable - NOT the battery end!!!!!!!"
  1. "By the vehicle end I mean the cable coming FROM the vehicle ground to the battery"

There yah go. The disconnected battery end of the ground cable is touched to the positive cable end. Since the battery is now not grounded there is no conducting circuit. Right? phil

Reply to
Phil Kangas

That is basically it - no circuit through the battery system - and a short across the caps in the ECU to drain them

Reply to
Clare Snyder

Really? I see a big explosion. Clare said to take the disconnected vehicle end of the cable, not the battery end and touch it to the battery positive. If you take the disconnected battery end, which is what you would be disconnecting normally, and touch it to the positive, then you'd get the desired effect, bleeding off any charge stored in caps and such. I doubt it's required though.

Reply to
trader_4

He said it right. He's discharging the car, not the battery.

Without the battery connected, the car won't have much charge but it can have enough to hold settings, and the goal was to reset the transmission.

Reply to
micky

No, he did not say it right:

If

What does "the vehicle end of the ground cable, not the battery end" mean? First, you would not disconnect the vehicle end of the ground cable to begin with. It's connected to the chassis and usually not even readily accessible. You would disconnect the BATTERY END. And then touch that to the positive battery post, with the positive cable still connected. And if you did disconnect the vehicle end of the ground cable, not the battery end, and shorted that to the positive battery terminal l like he sadi, you would have a direct short across the battery, fireworks and possible explosion.

Reply to
trader_4

This was all just confusion about a poorly worded sentence and mostly unnecessary in the first place. The capacitors in these ECUs won't carry that load for more than a second or two anyway. If you disconnect that battery for 10 seconds, everything that was going to reset will reset. These days I suspect a lot of those settings are in Flash and that isn't going to reset until you reset it. As for the transmission in a 2000 Honda. It was reset in a couple of seconds every time I did it. I am guessing a Toyota would be the same.

Reply to
gfretwell

snipped-for-privacy@aol.com > This was all just confusion about a poorly worded sentence and mostly unnecessary in the first place.

Right. And now it has been 'Clarified' for all. Clare is a good guy, just busy as all get out. Now on to the next subject and drop this one. Thanks Clare... ;>) phil

Reply to
Phil Kangas

+1

That's been my experience with codes that i've reset in various modules, including tranny too.

Like others have said, the car needs to go to a dealer or competent repair shop. If they read a code, then they should be able to tell the customer what that code typically means is wrong. It could be anything from a bad connection to a tranny that's kaput. If it's the latter and you're a shyster, I guess you could sign up for one of those great auto warranty company plans, drive around in limp mode for a couple months, then take it for repair.

Reply to
trader_4

Or in a recent case, a cobweb in a sensor port.

Reply to
Scott Lurndal

On most of the newer vehicles it IS in flash (NVRAM) and will not reset by simply disconnecting the battery. Basically on any that can be "reflashed" with new microcode. I don't think year 2000 vehicles had that capability (better than 90% sure, but not CERTAIN.)

Some vehicles in that time period DID have "persistent" memory - with basically a supercapacitor to hold memory when the battery had to be replaced or disconnected for service - to avoid the ECM losing all it's adaptive settings, and the radio losing all it's presets, and the memory seats and pedals etc from losing all their settings. These vehicles MAY have held their codes for up to, say, half an hour. Shorting the supply to ground drained the charge on the capacitor, deleting the codes and all other saved settings.

Sometimes a vehicle's memory went into a "limbo" state when power was disconnected - or even with power surges - and shorting the memory was the only simple way to restore the system to an operable state, since the ECU didn't even know how to communicate with the scanner.

Not a common occurence, for sure - but a possibility none-the-less. On a 2018 vehicle disconnecting OR shorting is unlikely to clear ANY codes or ECM settings (or BCM either)

From 2009-2010 on up there are also "permanent DTCs" than can NOT be cleared - even with a scan tool. The only way to clear them is to repair the problem, delete all current, history, and pending codes, and then successfully complete a "drive cycle" to prove to the computer that the fault has been repaired. These are "generally" "hard emission faults". They are generally identifiable by the code NOT starting with a letter.

Reply to
Clare Snyder

My 97 Honda doesn't remember shit after the most brief disconnect. When I still had the factory radio that was a real pain in the ass because there was a secret code you needed to enter to get it going again. I chucked it and put in an MP3 player pretty fast. I am not sure who would want to steal that radio in the first place. It sure wasn't easy to get out (pre DIN) and there was nothing special about it. It didn't really matter tho since I was already playing MP3s in the car when I bought the car and I was only using the AMP, via a cassette adapter, from a PC in back.

Reply to
gfretwell

'97 was the first, or possibly second depending on the model, Honda with full OBD2 compatability. Mode 6 became standard in 1998. Things changed very little for the next 5-8 years, and then "all hell broke loose" with Mandatory CanBus in 2008 (actually 2001 for European cars) and EOBD and OBD3 ----- and LOTS of fun.

Reply to
Clare Snyder

I have never had a need to plug anything into the OBD port on that Honda. The only thing that really "failed" was the hydraulic cylinders for the clutch, a leaking radiator and the door handles. I did replace the oil filter housing but that was just to stop a drip in the driveway. The belt job was preventive maintenance like the tires.

Reply to
gfretwell

In just under 8 years my '96 Ranger has thrown two codes. A leaky evap hose and a bad temperature sensor - both of which I would not have caught without the CEL coming on (and the last one WAS hurting gas mileage before it got to the point it stopped in the middle of the road just as the CEL came on - - -

Reply to
Clare Snyder

It is what I said before. Generally speaking, the electronics are making cars easier to fix. They usually tell you where they hurt. I am sure if you do it long enough you have plenty of stories of things that should have been caught and weren't but it is not the olden days where you just had to guess what to fix and it was all shades of gray.

Reply to
gfretwell

HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.