LOST JEEPS :: View topic - No glow plug light

papaindigo wrote:

NOTE - for those that disconnect the MAF it's not a good idea to do so unless you also load a free ECU flash that will disable the MAF CEL. The obvious problem of driving around with the CEL on all the time due to the MAF being unplug is as noted you cannot see the CEL come on for other reasons.

Pap, if I understand it correctly, none of the currently available DIY tunes disables the MAF function or its associated DTCs! The DIY tunes only disables the DTC's for unplugging the EGR and FCV and / or when totally removing them. After unplugging them and / or removing them, (EGR & FCV) the MAF should be plugged back in so the OBC can still monitor incoming air flow. Not sure it is good for anything, but it still must be left in service to prevent tripping a DTC... :roll:

If I am wrong on this, maybe Marco can comment and set us straight?

I believe I read in the past that the GDE tunes DO disable the MAF and / or its associated DTC???

But you are correct, if you already have a hard DTC set keeping the CEL light on all the time, if another one happens to be triggered, you can only know it by reading the codes with a proper scanner...

:SOMBRERO:

Author:	Reckard [ Fri Dec 01, 2017 10:33 am ]
Post subject:	No glow plug light
The glow plug light has stopped coming on at initial startup. Not to heat the plugs but just to indicate it is working as with all the dash lights when the key is first turned on. It use to but does not now. I read something about a relay. I cannot find it in the manual where the other relays are listed like in the distribution center. I also cannot find a fuse relating to it. Am I off completely? It is getting cold here so I know I better fix it soon. Thanks, Randy

Author:	flash7210 [ Fri Dec 01, 2017 11:25 am ]
Post subject:	Re: No glow plug light
If there was a problem with the glow plugs, whether it be the relay or the plugs themselves, a code would be set and the CEL should be on. As has been mentioned here several times before, the glow plug light cycles very quickly as soon as you turn the key on. Blink and you will miss it.

Author:	Reckard [ Fri Dec 01, 2017 12:39 pm ]
Post subject:	Re: No glow plug light
The cel is on due to the MAF being unplugged. It use to come on for the split second you mention and now does not. I cannot get the key cycle to show the codes. I bought a scanner that was mentioned on here to work with the CRD but it will not connect and show the codes. Is there a glow plug relay or fuse?

Author:	flash7210 [ Fri Dec 01, 2017 12:47 pm ]
Post subject:	Re: No glow plug light
There is definitely a relay. Its fastened down in the area between the battery and master cylinder. Some call it the glow plug module. If you have a android phone/tablet, get a ELM327 OBD Bluetooth adapter and the TorquePro app. Reading codes is just one of the many things that its excellent at doing.

Author:	WWDiesel [ Fri Dec 01, 2017 12:51 pm ]
Post subject:	Re: No glow plug light
From the FSM: Ignition Switch On (Engine Off) When the ignition is turned on, the ECM activates the glow plug relay for a time period that is determined by engine coolant temperature, atmospheric temperature and battery voltage. The GP relay is not in the Power Distribution Center, it is a single relay located attached to the rear bottom side of the battery tray right below the master cylinder. (see pictures)

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Author:	papaindigo [ Fri Dec 01, 2017 2:43 pm ]
Post subject:	Re: No glow plug light
Step back a bit. Either a) the GP light is coming on and you are not noticing it (doubtful as you are aware it comes on briefly), b) the GP light is burned out but the GPs are working fine, or c) GP light is burned out but GPs are NOT working fine. Ignore a) For b) invoke the bulb/gauge test by holding the trip odometer button down while turning the ignition which will cycle all the lights and gauges. If GP bulb is good it should light. If not go to http://colorado4wheel.com/manuals/Jeep/KJ/ and download my tech tips PDF. In bookmarks go to Instrument cluster removal and bulb replacement - includes LED bulb replacement for how to replace GP light LED. For c) if the GPs are not working right Flash is correct that will throw a CEL/code but if your MAF is unplugged you won't be able to "see" the problem via the CEL because it's always on. Choices a) plug MAF back in and drive for say 5 days for enough engine cycles to turn off CEL caused by MAF, if CEL does not go off you probably have a GP problem or b) possibly check for current at key on to GPs with volt/ohm meter, I'll leave to others how to do that check or c) get the code reader Flash mentions or find a shop with a DCJ code reader or equivalent (not just any old reader will do) to check for codes other than MAF. NOTE - for those that disconnect the MAF it's not a good idea to do so unless you also load a free ECU flash that will disable the MAF CEL. The obvious problem of driving around with the CEL on all the time due to the MAF being unplug is as noted you cannot see the CEL come on for other reasons. PS as WWdiesel notes below my memory or his may be off re. DIY tunes and MAF light but as he says let's see what Marco says.

Author:	WWDiesel [ Fri Dec 01, 2017 3:16 pm ]
Post subject:	Re: No glow plug light
papaindigo wrote: NOTE - for those that disconnect the MAF it's not a good idea to do so unless you also load a free ECU flash that will disable the MAF CEL. The obvious problem of driving around with the CEL on all the time due to the MAF being unplug is as noted you cannot see the CEL come on for other reasons. Pap, if I understand it correctly, none of the currently available DIY tunes disables the MAF function or its associated DTCs! The DIY tunes only disables the DTC's for unplugging the EGR and FCV and / or when totally removing them. After unplugging them and / or removing them, (EGR & FCV) the MAF should be plugged back in so the OBC can still monitor incoming air flow. Not sure it is good for anything, but it still must be left in service to prevent tripping a DTC... If I am wrong on this, maybe Marco can comment and set us straight? I believe I read in the past that the GDE tunes DO disable the MAF and / or its associated DTC??? But you are correct, if you already have a hard DTC set keeping the CEL light on all the time, if another one happens to be triggered, you can only know it by reading the codes with a proper scanner...

Author:	flash7210 [ Fri Dec 01, 2017 4:09 pm ]
Post subject:	Re: No glow plug light
WWDiesel wrote: papaindigo wrote: NOTE - for those that disconnect the MAF it's not a good idea to do so unless you also load a free ECU flash that will disable the MAF CEL. The obvious problem of driving around with the CEL on all the time due to the MAF being unplug is as noted you cannot see the CEL come on for other reasons. Pap, if I understand it correctly, none of the currently available DIY tunes disables the MAF function or its associated DTCs! The DIY tunes only disables the DTC's for unplugging the EGR and FCV and / or when totally removing them. After unplugging them and / or removing them, (EGR & FCV) the MAF should be plugged back in so the OBC can still monitor incoming air flow. Not sure it is good for anything, but it still must be left in service to prevent tripping a DTC... If I am wrong on this, maybe Marco can comment and set us straight? I believe I read in the past that the GDE tunes DO disable the MAF and / or its associated DTC??? But you are correct, if you already have a hard DTC set keeping the CEL light on all the time, if another one happens to be triggered, you can only know it by reading the codes with a proper scanner... Correct. The DIY tunes do not remove the MAF codes. The GDE tunes do. But once you have removed the EGR and FCV and loaded the appropriate DIY tune, then you can plug the MAF back in and not worry about it.

Author:	Reckard [ Fri Dec 01, 2017 4:12 pm ]
Post subject:	Re: No glow plug light
Is the "Marco" you are referencing the same as did the Smarty for the Cummins Dodge? I have a Jr....

Author:	Billybob [ Sat Dec 02, 2017 8:25 am ]
Post subject:	Re: No glow plug light
What year is your KJ? The "key" method to pull codes stopped working around 2006 I believe. Testing the cluster as stated by holding in the Odometer Trip reset button while turning ignition ON should light up all Leds!

Author:	WWDiesel [ Sat Dec 02, 2017 12:04 pm ]
Post subject:	Re: No glow plug light
Billybob wrote: What year is your KJ? The "key" method to pull codes stopped working around 2006 I believe. Testing the cluster as stated by holding in the Odometer Trip reset button while turning ignition ON should light up all Leds! My 05 instrument cluster bulbs are OEM incandescent, not LED's!

Author:	papaindigo [ Sat Dec 02, 2017 3:22 pm ]
Post subject:	Re: No glow plug light
WWdiesel I suspect we are talking apples vs. oranges. The instrument cluster lights that illuminate the cluster at night are incandescent however the lights for the "warning" things (CEL, GPs, etc) that are on the cluster circuit board are LED. The LEDs rarely burn out but if they do the dealer solution is to sell you a new instrument cluster for like $700 + labor. Some years back lgoodbar figured out how to replace burned out LEDs and that's whats in my tech PDF.

Author:	Reckard [ Mon Dec 04, 2017 7:55 am ]
Post subject:	Re: No glow plug light
Well I did the gauge light check and all lights are good. It was cold yesterday morning and the glow plugs/light heated for about three seconds and it started fine so you guys were right again... Thanks Randy

Author:	aaronguy2k1 [ Mon Dec 04, 2017 9:28 am ]
Post subject:	Re: No glow plug light
I've never seen my glow plug light until doing the light check. My plugs work, have failed, and have been fixed. I don't know what else affects that light, I just tell myself it's disabled for power and MPG.

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Author:	WWDiesel [ Mon Dec 04, 2017 12:04 pm ]
Post subject:	Re: No glow plug light
aaronguy2k1 wrote: I've never seen my glow plug light until doing the light check. My plugs work, have failed, and have been fixed. I don't know what else affects that light, I just tell myself it's disabled for power and MPG. Glow plug function would never be disabled for neither power or MPG! If your GP system is not working properly, you could have another problem!