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Limp home mode causes

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Old Feb 29, 2004 | 07:11 PM
  #1  
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Limp home mode causes

What kind of things will put the ECM into limp home mode? I just swapped ECMs and I STILL can't get any datalogs in WinALDL or TunerPro RT. This is bizarre.
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Old Feb 29, 2004 | 09:54 PM
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Re: Limp home mode causes

Originally posted by jeepguy553
What kind of things will put the ECM into limp home mode? I just swapped ECMs and I STILL can't get any datalogs in WinALDL or TunerPro RT. This is bizarre.
Just about anything.
There's actually 3 ecm modes, normal, fail soft and limp home. LH meaning that the ecm isn't using the processor, and is using the other analog hardware in the box.

Might try disabling all the malfunction flags and see if you can get it to link.
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Old Feb 29, 2004 | 10:43 PM
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From: Rockport, TX
Car: 1980 Jeep CJ7
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Transmission: TF727 set for kill...let's get it on!!!
Okay...I'll do just that...thanks Grumpy.
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Old Feb 29, 2004 | 11:12 PM
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Re: Re: Limp home mode causes

Originally posted by Grumpy
Just about anything.
There's actually 3 ecm modes, normal, fail soft and limp home. LH meaning that the ecm isn't using the processor, and is using the other analog hardware in the box.

Might try disabling all the malfunction flags and see if you can get it to link.
Got any idea what mode is used when the timing wire is disconnected for setting the base timing?
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Old Mar 1, 2004 | 01:12 AM
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Re: Limp home mode causes

Originally posted by jeepguy553
What kind of things will put the ECM into limp home mode? I just swapped ECMs and I STILL can't get any datalogs in WinALDL or TunerPro RT. This is bizarre.
Like said above, the things that will do it are either a hardware failure or an eprom failure. In the case of the eprom failure the ecm keeps reseting and trying to get the correct checksum untill hell freezes over and you get the flashing SES light. If the light goes out when the motor is going then your not in limp home. Its wierd that it wont xmit data. Maybe something wrong with the cable or the computer (PC, not ecm) your using? Both my 8746 and 8063 transmit all the time.
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Old Mar 1, 2004 | 07:34 AM
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Re: Re: Re: Limp home mode causes

Originally posted by brennanw
Got any idea what mode is used when the timing wire is disconnected for setting the base timing?
Soft fail.
The processor is still in the loop.
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Old Mar 9, 2004 | 09:29 PM
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From: Rockport, TX
Car: 1980 Jeep CJ7
Engine: AMC 360 with GM TBI
Transmission: TF727 set for kill...let's get it on!!!
Re: Re: Limp home mode causes

Originally posted by dimented24x7
Maybe something wrong with the cable or the computer (PC, not ecm) your using?
This may very well turn out to be the case. We'll see in a few days. I just got a "new" laptop, though and I find it difficult to believe that TWO PCs could do EXACTLY the same thing. I also just got a new ECM...it's in the ECM clinic for minor outpatient surgery. We'll see how it turns out when the ECM is discharged from the clinic.
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Old Mar 10, 2004 | 06:26 AM
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Re: Re: Re: Limp home mode causes

Originally posted by jeepguy553
This may very well turn out to be the case. We'll see in a few days. I just got a "new" laptop, though and I find it difficult to believe that TWO PCs could do EXACTLY the same thing. I also just got a new ECM...it's in the ECM clinic for minor outpatient surgery. We'll see how it turns out when the ECM is discharged from the clinic.
Last week, I had two ignition modules that didn't work in non-EST mode, I've had 4 bad O2 sensors in a row, several bad TPSs in a row, not to mention when I was working, on customer cars, I'd hit 5-6 of the same failures in a row.

Just never say never, or assume anything.
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Old Mar 10, 2004 | 06:37 AM
  #9  
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From: Rockport, TX
Car: 1980 Jeep CJ7
Engine: AMC 360 with GM TBI
Transmission: TF727 set for kill...let's get it on!!!
That sucks, Grumpy! It sounds like you luck is running the same course as mine lately.
Once all these little bugs get ironed out, it looks like everything should be great. Spring break is coming up and I'll have about 10 days to goof off and work on the Jeep. ECM tuning....cage welding...maybe an axle swap or two...
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Old Mar 11, 2004 | 12:05 PM
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From: Rockport, TX
Car: 1980 Jeep CJ7
Engine: AMC 360 with GM TBI
Transmission: TF727 set for kill...let's get it on!!!
Bill, check your PMs. I found you a D300 xfer case...sorry for the OT post guys.
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