JohnnyLT

Hey guys,

I'm new to the forum, just purchased a 2001 Jeep Grand Cherokee Laredo 4.7 V8. The previous owner didn't know much about cars considering when I ran the ODB 2 scanner it popped 7 codes. I managed to get rid of all the codes except 1 which is the P1689 that refers to no communication between the PCM and the fuel injector module. Not sure where to start, jeep runs fine and i replaced the fuel pump relay, battery temp sensor, evap purge solenoid and the auto shutdown relay. Any advice and suggestion would be helpful. Thanks

-Big John

dave1123

Welcome to CF!

I just ran that code and as far as I can tell, it pops up as "battery disconnected in the last 50 starts" except for the Dodge diesel trucks. AFAIK jeeps don't have an injector pump module and I don't believe they have a fuel pressure sensor either. The PCM just triggers the pump to run but doesn't monitor it for pressure.

I'd just clear the code and not worry about it.

UNLESS YOU HAVE A DIESEL, which you don't seem to have because you stated it was a 4.7.

Bustedback

Is the check engine light on, or is this just a code that popped up with your code reader?

JohnnyLT

Yea I have a check engine light on. I've already tried clearing it 3 times. No luck.

Bustedback

This isn't a duel fuel vehicle, is it?

JohnnyLT

duel fuel?

Bustedback

Gasoline/propane. I'm guessing it's not a duel fuel. The reason I asked is because where I work I have a bunch of Ford F-150 pickups that are duel fuel. They all have seemed to have a code very similar to the one you have pop up. They had a separate ECM for the propane system. Since they never even used the propane option I would just unplug the propane ECM and clear the code.

JohnnyLT

No it definitely doesn't have dual fuel tanks.

Nichesound

Did you ever fix this problem? I had a similar problem with a 4.0Liter 2001 Grand Laredo, it kept showing a yellow trouble light..every time I had to get an emissions check for my tabs done in Seattle Washington, no one could fix it....it took 5 years, and twice I paid the $150 to have them come up with nothin!!!! One guy said he would find it for free...than never happened! I did fix it..eventually...I decided that I wanted to upgrade the injectors with new Bosch 4 hole injectors.....I bought them on eBay for $92bucks plus shipping…great buy I thought! I had a garage do the work for get this $62 bucks...I thought that it was well spent money...So some history about that yellow light and ‘the code’….okay the code would always be the same, it showed the code for a back fire in various cylinders, but it never did 'back fire' and always ran great...so I had them there injectors a waiting their turn for the garage man to install...so one day I had to have a service call, window motor and relay of course...damb cars this is the second one, driver and then the passenger front....okay so I says how much for the injectors...the man says….$62 bucks – I says…....okay --- so I get this done and I get the Jeep back, of course they zeroed the codes.....next I am waiting for that darn YELLOW LIGHT TO APPEAR!!!!! And I am waiting…driving and waiting…baited breath and all…waiting and waiting…watching and waiting…as you see it would ALWAYS COME BACK!! And then… Lo and Behold, it has been over 120 miles and holding...no yellow light! So all along it was them darn oneholerinjectors! I had them even cleaned (injectors, and whatever else they clean) at one of them emission-bring-it-in-to-have-it-checked-and-send-them-off-after-paying-the-$150-bucks-so-I can-get-the-tabs...so so so - so the moral of the story is ...don't give up ...and someday do change them injectors..it will save you a huge bill, and a new this and that and the other thing! I had all kinds of stuff changed out, for naught! Good luck and the creek didn’t rise!!! Johnne in Seattle