1997 Swift DTC trouble

[iseestars]

I have a 97 Swift 1.3L Auto. I have a code p1250- EFE Heater circuit. Can anyone tell me what to test, or how to diagnose the fault.. I have a scan tool to read, and erase the codes. I have a Chilton brand manual- and it has NO info on diagnosing. So, if anyone has info, or a link to a SHOP MANUAL, that they can share with me thats would be most appreciated. thank-you

[lumpylarry]

WIRING DIAGRAM

CIRCUIT DESCRIPTION
In this system, air/fuel mixture to be drawn into the engine combustion chamber is warmed up to improve the burning efficiency while engine warming up. Located between the throttle body and the intake manifold, EFE heater is turned ON and OFF by its relay which ECM controls. EFE heater is turned ON while engine warming up (when coolant temp. is low and engine speed is higher than specified idle speed) and it warms air/fuel mixture which passes through it and as a result, fuel is atomized better.







DETECTING CONDITION AND POSSIBLE CAUSE

DTC CONFIRMATION PROCEDURE


Turn ignition switch OFF.
Clear DTC with ignition switch ON.
Check vehicle and environmental condition for:
indication of fuel level meter in combination meter: 1/4 or more
Altitude (barometric pressure): 24OOm, 8OOOft or less (560 mmHg, 75 kPa or more)
Ambient temp: -10°C, 14°F or higher
Intake air temp: 50°C, 122°F or lower
Start cool engine and warm it up to normal operating temperature
Check pending DTC in "ON BOARD TEST' or "PENDING DTC" mode and DTC in "DTC" mode.

[iseestars]

Update, I've been draggin my feet on this, but here is where I am now. The 30amp PTC fuse was open. I changed it, and in less than a minute, at idle, it popped. I unplugged the heater at the manifold, and so far it has not blown the fuse- it does reset the code P1250. I have yet to read the heater impedence- although I am unsure what the value should be. Anyone wanna measure theirs and tell me what you get? Thanks!!

[iseestars]

Many Thanks to LL for your response!!

[Brian124]

Originally Posted by lumpylarry

WIRING DIAGRAM

CIRCUIT DESCRIPTION
In this system, air/fuel mixture to be drawn into the engine combustion chamber is warmed up to improve the burning efficiency while engine warming up. Located between the throttle body and the intake manifold, EFE heater is turned ON and OFF by its relay which ECM controls. EFE heater is turned ON while engine warming up (when coolant temp. is low and engine speed is higher than specified idle speed) and it warms air/fuel mixture which passes through it and as a result, fuel is atomized better.







DETECTING CONDITION AND POSSIBLE CAUSE

DTC CONFIRMATION PROCEDURE


Turn ignition switch OFF.
Clear DTC with ignition switch ON.
Check vehicle and environmental condition for:
indication of fuel level meter in combination meter: 1/4 or more
Altitude (barometric pressure): 24OOm, 8OOOft or less (560 mmHg, 75 kPa or more)
Ambient temp: -10°C, 14°F or higher
Intake air temp: 50°C, 122°F or lower
Start cool engine and warm it up to normal operating temperature
Check pending DTC in "ON BOARD TEST' or "PENDING DTC" mode and DTC in "DTC" mode.

Thanks for the info.I have 2004 Swift.This info will help me too.

[CULTUSTOM]

I have the same problem. Unplugging the EFE heater connector solves the fuse-blowing issue but the P1250 DTC will re-appear as soon as the engine temp is warm, when the EFE-off signal voltage is unable to be measured. My EFE heater falls in the middle of specified normal electrical resistance (it is 1.6 ohms at 68 degrees F), but I suspect the problem is that the EFE heater is shorted to ground through a faulty TB gasket; this would explain the PTC fuse blowing as soon as you start the engine. I am ordering a new EFE upper and lower gasket, which are about $10, a lot cheaper than assuming a need to replace the $300 EFE heater.

[iseestars]

Check this out. On the wiring digram you can see that output side of the relay feeds the heater, and the PCM. I am guessing its looking for current flow, or a load. As I mentioned earlier I have unplugged the heater pigtail and the fuse no longer opens. So, I put a 194 light bulb ( only cause thats what I have a socket and wires for) into the now vacant heater pigtail. And PRESTO!! the service light went out!! I have cleared the code and am road testing now.