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  #1  
Old 02-08-2013, 07:20 AM
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Low tachometer reading

Hi guys

I just joined the forum after I found solutions here concerning troubles I had
with error code P1499. I realized through that there are lot of guys out there which share my love for jeep grand cherokee and have experienced same problems I have had and are very helpful and willing to share their knowledge.

I live in Iceland and have a Grand Cherokee overland 4.7l, 2004. I imported this car from USA in 2007, then it had 60.000 miles. I love this car and it has been running relatively smoothly expect for I had to replace the starter and a water pump besdies normal maintainance. Now it has 114.000 miles and I had to change head gaskets and timegear. It was done in private garage by mechanic. It did cost me about the half of the retailprice.
When I got the jeep back I noticed that the Tachometer was showing just above 300 rpm but before the repair it was rock steady on 600 rpm. Inspite of this low reading the engine is running smoothly and seems to be running higher speed than the Tachometer indicates and the consumption seems to have increased. Does anybody know what is going on here ??

All the best,

Björn
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Old 02-08-2013, 07:57 AM
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Re: Low tachometer reading

I don´t think that the engine will even idle at 300 rpm and for sure not that smooth. So there seems to be a problem with the indication. Since the engine runs smooth, it seems that the rpm signal itself is ok. Start with the instrument self test, to be sure that the indicator/electronics are ok: with ignition switch in OFF, press the odometer reset button and while pressing it, switch the ignition in ON. Now all indicator lights will come on, the odometer will count 1111111, 222222 etc and the gauges will go to full scale and return to normal. As soon as the test starts, you can release the odometer reset knob. If this seems to be ok, then we have to see further.
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Old 02-08-2013, 03:33 PM
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Re: Low tachometer reading

Thank you Frank for your kind response and advice.

I tried the suggested reset procedure and the odometer counted from 111111 to 888888 and then DONE. But sadly the tachometer still shows 300 rpm. Another strange things is also showing up according to my wife (which is driving the car on daily basis). She claims that the blower fan motor stops (has happened two times) for seconds and then starts again. I dont know if this is connected with tacho problem but to me non mechanic this could be indicating some bad connection problem somewhere.
Some further suggestions ? It has been mentioned to me that cause could be bad earth connection. I tried to connect the earth poe on the battery directly to engine but nothing changed.

Regards,
Björn
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Old 02-08-2013, 05:59 PM
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Re: Low tachometer reading

Does it look as if the tacho pointer is stuck at 300 rpm? That is doesn´t go over the 300 rpm during the test, shows that the problem is in the instrument cluster.
All gauges are getting their data from the PCM via the PCI data bus. If all other gauges work normally, i would expect a problem or with the gauge itself, or with the electronics behind it.
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Old 02-09-2013, 05:21 AM
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Re: Low tachometer reading

Hi again Frank

I think you are right, it must have something to do with the gauge itself or electronics behind it. I ran the test/reset again observing the tacho. It went up to about 6700 but not to full 7000 rpm. Indicating some calibration problem either mechanical or electronical. I will go to a garage next week where I know they have the correct equipments and expertise to read and diagnose the car, if possible. I will keep you informed if you are interested.

Thanks for your help !

I wish you all the best,

Björn
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Old 02-09-2013, 06:38 AM
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Re: Low tachometer reading

Hi Björn, yes please keep us updated on this one. With the final results from each problem we can help others out again.
Does the garage where you will be going to have special instrument cluster test equipment? Probably with the Chrysler DRBIII scanner some extra tests of the cluster will be possible. Don´t know of any repair possibility of the cluster, its normally just changed out.
Still strange though that this problem started after the engine problems you´ve had.
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Old 02-09-2013, 08:28 AM
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Re: Low tachometer reading

I will keep you posted. I dont know what kind of equipment or computers the garage has but the owner is clever and educated in electronics. He solved my "airbag light problem" in 5 minutes after the Chrysler garage had spent 3 hours and expensive spareparts, without solution.

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Björn
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Old 02-09-2013, 09:35 AM
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Re: Low tachometer reading

Hi Björn, was just reading the thread again and saw that you also have sometimes problem with the blower motor. Did this also start after the engine troubles?
The blower motor controller on the AZC system is well known to give problems of a melting connector. Seems that the connector doesn´t fit that well, causing some resistance and due tot this it will heat up and melt the plastic. You can easily see this connector when looking up from the passengers foot well. You will see the blower motor with just besides it the controller.
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Old 02-09-2013, 11:19 AM
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Re: Low tachometer reading

Hi Frank

Yes the blower motor started showing some strange behavior after the engine trouble but it is only a week now from the engine repair. But as I said I have not observed that yet myself, only my wife and she is a piano player and sometimes gives some strange descriptions of the cars behaviour :-).
I will take a look at the connector but I assume that during the repair this connector does not have to be disconnected.
Actually, the reason for I suspect some electronic connecting problems is that when I got the jeep back the engine light was on and I found out myself (after some googling and error code P1499) that the mechanic had forgotten to connect the hydraulic heater fan valve cable and after two days the car did not start because he had not connected the battery properly. So no wander I suspect him to have screwed up some other connections or even the time chains not correctly in place. But he was cheap :-) compared to commercial garages but according to him he has done this several times before.

Kind regards,
Björn
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Old 02-11-2013, 09:50 AM
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Re: Low tachometer reading

Hi Frank

I checked the blower motor control connector. You were quite right it has bad connections and was hot. I tried to disconnect it but did not manage probably because the plastic had already melted. Sometimes all things go wrong at the same time.
I went to the "clever" electric mechanic in my lunch time today. His diagnostic just by taking a look and listen to the engine: Engine is idling perfectly and at a higher speed than the Tacho indicates and the fault is in the electric motor moving the needle. He was familiar with the blower control connector problem and told me how to fix it and offered to do it for 1-2h hour work ($80-120). On my way back home (short distances here in Iceland) I dropped by at the Chrysler spare part shop to by a new connector. They told me that because of the frequent fault of this connector it is not sold anymore and offered me a new type of controller including connector for about $200. I jumped on that and intend change it to night. Should be relatively easy expect I have not figured out yet why it comes with extra cable and connectors from the controller to the blow motor.

Thanks again Frank for useful and skilled advice.

All the best,
Björn
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Old 02-11-2013, 04:26 PM
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Re: Low tachometer reading

Didn´t expect you to be that quick in buying the cable/connector. There was in fact a simple and cheap way to repair it. I think there is even a writeup about it in the DIY section. You could easily discard the connector and just solder the wires to the controller pins or even directly to the control board.
Take care to connect each wire at the right place, otherwise the blowermotor will rotate into the opposite direction and you won´t get any air.
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Old 02-11-2013, 05:20 PM
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Re: Low tachometer reading

Hi Frank

Yes I had already seen the fix in the DIY section but decided anyhow to buy a new one because they claim the new should be a improvement. I have already mounted it and it seems work fine. I took the old one apart and it was quit melted and one of the pin on the control board was loose and burning signs around it.
I might have been able to fix it and would probably have done that if I would have had same experience and knowledge I have now at the begining :-)


Regards,
Björn
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