no pip signal HELP!

matty872 · Post by **matty872** » Fri Oct 17, 2008 10:25 pm

Hi I have a V3 unit but when I connect the pip wire to the MJ the voltage disapears. The edis is putting out 12v ign on and about 6v engine running as it should when not conected to the MJ. I have replaced the rs232 and no difference, In the configurator the rpm always reads about 500rpm. I was checking around the board and pin 4 on the U1 appears to be outputing 4v is this correct? I have looked through the web sit and tryed what other people have done,I am really getting fustrated trying to sort this so would really appreciate some help thanks.

alexander · Post by **alexander** » Fri Oct 17, 2008 10:41 pm

the configurator wont go below 500rpm, so a reading of 500 rpm really means no signal.

matty872 · Post by **matty872** » Sun Oct 19, 2008 7:25 pm

yes I had read something about that on the forum, I need to find out why the MJ is killing the pip voltage, could it be a faulty processor?

Post by **brentp** » Sun Oct 19, 2008 10:02 pm

Pin 4 on U1 (the processor) is an input, so it accepts the voltage from the RS232 transceiver. It goes like this:

PIP->RS232 transceiver->Processor

As you can see, the processor is not directly connected to the PIP line- it's buffered by the RS232 transceiver. So, it cannot 'kill' the PIP signal.

Do you lose the PIP signal with the RS232 transceiver (U2) removed?

Moreover, what is the history of this V3 controller? was it working correctly in the past? on this engine or a different one?

Let us know-

matty872 · Post by **matty872** » Mon Oct 20, 2008 7:27 pm

Thank you for your responce. I have tryed removing the rs232 and the signal is ok, but when i done it I could measure 4v coming out of the input on the prosessor. The unit was brought from someone unused, but he brought it built. There is a sticker on the back of the unit that has an email address for a martin and the loom was unused. I can comunicate with the unit fine and put maps on it also the map pressure reads ok in the configurator.I hope thats of some help to you.

Post by **brentp** » Mon Oct 20, 2008 8:42 pm

I will re-check the signals on a working unit and post back.

In the meantime, would you by-chance have a spare EDIS module to test against?

Post by **brentp** » Tue Oct 21, 2008 6:51 am

Hi Matty,

PIP signal when running should be about 4.4v. On the side feeding into the processor it should show 2.8v while running.

Double check the wiring- ensure you don't have a wiring mix-up on the EDIS connector- i.e. you are actually tapping into the correct pin for the PIP signal. The PIP signal input of the MJLJ has a fairly high impedance- so it should not load down the PIP signal from the EDIS module.

A valuable test would be to try a different EDIS module.

Let us know what you find out.

matty872 · Post by **matty872** » Tue Oct 21, 2008 9:39 pm

Hi brent.

I have checked over my wiring and it is ok. The edis was removed from a working car so it should be ok but I can try borrow another one. I don't think I was very clear about what I had tested in the MJ, If I just power up the MJ nothing else wired up and the RS232 (U2) removed I can measure 4v coming out of the input (pin 4) of the prosessor (U1) which to me does not seem right.
thanks
matt

matty872 · Post by **matty872** » Thu Oct 23, 2008 8:38 pm

Have tryed the edis off my other car and no different. anymore ideas? Is it possible it could be the prosessor?

Post by **brentp** » Fri Oct 24, 2008 12:24 am

For the reasons explained before, it's doubtful the cause is the processor.

However, have you tried testing it with the processor removed but the MAX232 installed?

Regards,

matty872 · Post by **matty872** » Sat Oct 25, 2008 10:17 pm

All FIXED! It turned out to be a dodgy screened wire from edis to MJ it was shorting to the shielding.

A big thank you for your help.

Post by **brentp** » Sun Oct 26, 2008 5:02 pm

That's excellent- we were running out of the standard troubleshooting steps on the MJLJ.

Curious- you identified the problem as the shield shorting the signal- how do you think that correlated with removing the MAX232 chip? Were you just moving the wiring harness enough to cause the shield to 'un-short' by chance?