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How to delete fault codes on 04 Grand Cherokee???

29K views 18 replies 11 participants last post by  Fireblade 
#1 ·
Does anyone know how, or is it even possible to, delete fault codes on a 04 Grand Cherokee (CRD if that makes any difference - I dont think it does), without buying a reader (ive got one but it does not want to talk to my jeep!
Ive recently had probs (see recent posts) but now the probs are solved I want to delete the fault codes as well. I know they will go after 40 cold start cycles (as long as faults dont reappear) but thats about a month for me!
Any ideas?................... and before anyone says "Disconnect the battery!" that does not work on 04 models. Have tried it on mine and two others from between 30 seconds to 24 hours and codes remain!!

Looking forward to your replies.:thumbsup:
 
#6 ·
Disconnecting the battery will work as long as the problems are actually fixed. Otherwise, I am sure there are autoparts stores in Great Britain who can do it for you, but again, if the battery disconnect doesn't work, clearing them with a code reader isn't going to work either....
 
#8 ·
If you dont know dont guess . It helps no one. Many cars I have had in the past could only be reset with a code reader rather than battery disconnect whether the probs were fixed or not. The idea is to stop regular Joes doing it and make them go to there dealers I would think. Just thought someone on here might know a trick.
 
#9 ·
^ I have to agree with there on that one mate, the disconnect thing doesn't work! It may do for the American but not over here in Blighty, tried it numerous times without result even left it over night and guess what.. it doesn't work!

With regards the Autoparts Stores no there ain't.. most of our "shops" buy the aftermarket readers like the Sun Diagnostics or Snapon Diagnostics very few will invest in Chrysler/Jeep equipment probably because its not a premium selling vehicle over here unlike BMW/Mercedes/VW/Audi/Ford.

Sorry for dispelling the rumour.... :-(
 
#10 ·
I wasn't guessing. I have never heard of the battery disconnect not working for jeeps. Whether it be American or otherwise. If the problem is actually fixed, it will work. If it doesn't work, the underlying problem is not fixed. There have been several hundred upon several hundred threads on this forum in my 3+ years of membership discussing this very issue. Do a search, Im sure you will find some.
 
#12 ·
No, does not work on 2004 UK spec Jeeps. Even tried leaving the headlight switch in the on position to make sure there was a high current drain..

And the reason is...............well I spoke to Jeep today (this is Jeep UK dont forget my American friends!!) and they told me the fault code memory does not rely on power (12volt) for its fault code memory so disconnecting the battery will not erase the codes no matter how long you disconnect the battery. You would physically have to de solder the memory chip from the curcuit board and short it to forget the codes. So there you have it...you either use a reader or wait for 40 code starts to erase the codes automatically.

Also dont forget that this is a Mercedes engine/transmission and ive yet to come across a german car that can have its fault codes deleted by battery disconnection although there will be a few older ones. I worked for a German car dealership for 14 years so I saw a few!!
 
#14 ·
alfaitalia said:
Also dont forget that this is a Mercedes engine/transmission
False. The WJ was designed before the merger. Production started 10 weeks after the merger. It is possible that some of the electronics were updated by Daimler.

Edit: The merger was announced in May and was official in November. The WJ had already been on sale for two months by then.
 
#16 ·
No, true. Its the same engine/tranny PCM (basically)as the Merc E270, The Merc ML270, the Merc Sprinter van etc etc. Dont forget that CRD production only started in 2002 ........ in sunny Austria.
 
#18 ·
This is now very late for the original question, but for those trying to reset error codes currently and wondering if disconnecting the battery works the answer is yes it does. Even on a UK spec 4.7L limited Grand WJ/WG. I have just done that after changing the Inlet Air Sensor (IAS) and the Throttle Position Sensor(TPS). The actual problem was the TPS, but changed both as a precaution. The error code was P0120 and after finishing I disconnected the battery for 10 mins, then reconnected. Immediately, the "check engine" light went out and checking for codes came up as nothing. Car runs fine now.Car is a European spec, supplied to the UK in 2002. Hope this helps.
 
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