andy2111

Hi everyone, I'm Andy from the UK and recently got myself a 991.1 (my intro post is here) and I have been reading through all the fantastic information in this thread for weeks. It has been incredibly helpful so thank you to all the contributors, and I will share anything new that I learn along the way.

I have now received my "Erisin" head unit, branded ZOHONG, with Andriod 12 and 8GB RAM and 128GB storage and I have also purchased the GPS and radio adapters as recommended in other posts. I also got the Erisin TPMS monitor and the USB DAB radio unit as well as a tiny USB hub (thought I'd experiment to see if it increases the number of ports given the TPMS and DAB are both USB)

I want to get the unit up and running on a "bench" before fitting it to the car. Many reasons for this, but mainly so I can more easily configure the software, download apps, play with settings and launchers etc. And also because I don't want to pull the interior of my car apart and spend time in and out of it until the weather here improves!

I have found the PCM 3.1 pin diagram as follows:



So I connected the VBAT and WAKE to +12V and GND to -VE on a 12V bench power supply.... but I can't get the unit to wake up. The fuse has not blown and there hasn't been any sparks or other sign of a bad connection.

I did a bit of Googling and for the original PCM unit I think the CANBUS needs to be present in some way - can anyone confirm if the same applies to these Android units please? And does anybody know if it is possible to fire up these head units outside of the car?

Thanks in advance for your help!

ZedZed

Hi Andy, Congrats on the 991. And huge kudos for finding that PCM 3.1 pin diagram - that is incredibly useful for all sorts of troubleshooting. Definitely saved that graphic in my HU folder!

I, too, would have connected the wires you did and expected it to power on. Odd. One thing I know for sure is that you can power the Android HUs on the bench, because I have seen numerous YT videos where they do just that. I can't see any other pins on that diagram that look even remotely necessary for the unit to power on, and I'd be surprised if it needs the canbus connections just to power up.

I can understand why you are not keen to remove the PCM at this stage, but it is very easy in the 991 and you can have it out in under 10 minutes. I think, if it were me, that I'd pull the PCM and connect the new HU to the harness just to test that the HU is firing up and is not DOA (although I have never heard of a unit being DOA). That doesn't solve the bench connection problem but it does prove conclusively that the unit is good. You can literally have the PCM in and out in 15 minutes - pull the side trims, undo the 4 torx bolts and gently pull.

EDIT: Here's a video showing the PCM removal process. Note that the side trim panels need to be pulled towards you once the clips have been released. Do not pull outwards at the dash end, or you may break the little retaining pole thing. Also note that the little pole thing engages into a small part that is removable (that is, it might fall out), so don't lose it. I normally remove it even if it doesn't fall out, just so I know where it is for the re-installation procedure. The Porsche Fakra clips are notorious for being very tight the first time they are removed - use a small flat-blade screwdriver to press on the little tab, while using a larger flat-blade screwdrive to gently pry at the join while holding, with your third hand, the body of the connector, and they will come apart just fine. Once you have done the first one, the others are plain sailing. The guy in the video has the PCM out in about 7 minutes, and he is taking it slowly for the purposes of instruction. Note that on the big quad connector, you have to pull down the retaining lever, and the two parts separate easily once you have done that. No force is required.

ZedZed

^^^^^^
Just a thought - most of these Ali Express sellers say that they test each unit prior to despatch. IDK if this is true or not, but they might, just to avoid any DOA problems and consequent returns. So it may be useful to contact your seller and ask them how they connect the units for bench testing.

andy2111

Thanks for the info and video ZedZed - BTW this is the source of the pin diagram in case there is more useful info there..

I think you are right, I will need to plug it into the car to do a quick test for DOA. I did a bit more reading and BMW and some VAG CANBUS systems use the CANBUS to send the "switch on" signal to the original head unit and I found a post somewhere which mentioned the same for PCM. The aftermarket units don't use this which is why they have the ACC/WAKE/KEY wire which lights up once the ingnition is on. So in theory the ERISIN-type units should not need CANBUS to wake them... but you never know, maybe they made them work just like the original PCM - only one way to find out!

I'll try at the weekend if I get a chance..

On another topic, I have found a few candidates for more OEM style buttons so I may order several sets (from China again) and share the pics in case it's helpful for others..

dogshyne

I ordered the mr12volt kit and couldn't make it work. It didn't come w/ extenders on the mount posts and my US car has Sirius radio so it made for a wonky install with the board touching the top of the sirius connector. When I buttoned it up and reconnected everything... nothing happened. the unit wasn't working inside the head unit. I had to disassemble and reach out to Mr12volt who hasn't gotten back to me in a week.

has anyone else had these issues?

Foosh

Yes, you need taller spacers for sat radio in the PCM. Try contacting the website below, which is for the authorized US installer for Mr12Volt.

https://acsbyroman.com

Edit: I just checked the above website, and when ordering Mr12Volt directly from Roman, his website has an option box to order the system with or without sat radio. That's the way he ensures that you have the proper spacers for installation.

You may be able to get the spacers more quickly from him.

Chuck245

The spacers are most likely the same than for the Isudar board. When I installed mine, the total length of the spacers that were included in the Isudar kit was 47 mm to clear the Sirius radio board. You can get spacers at https://rennlist.com/forums/panamera...l#post19124454 if mr12volt doesn't provide them to you.

ZedZed

Thanks for that link. Looks like there could be some useful info there. I already found something useful - for anyone with a backup camera failing to work as it should, and looking for the OEM wires that supplies power, in order to connect that to the new HU camera wire, check out the pin and associated wire marked as CVBS power in your pin diagram.

Oh yes! Please share. That would be a worthwhile mod to these HUs, at low cost too.


Please keep us in the loop regarding your installation.

ZedZed

Amazon sell boxes of standoffs for just a few dollars - might be quicker and easier.


You need the M2.5 standoffs so that the thread is right for the OEM motherboard.

ZedZed

I just looked through that thread. Wow. Although I have huge respect for the OP and his dedication to his project, I have to say that it seems like an enormous amount of work, requiring substantial knowledge and ability, not to mention cost - and the end result seems, to me, to still offer no more functionality than a low-cost Android aftermarket HU. I am biased, of course, and there is no way I have the skill set to do what the OP there is doing. And he does end up with a Porsche component in his car (although it is no longer OEM of course, since 991s didn't come with PCM 4.0 originally). Give me an Android unit that I can install in a morning, every time. It's just my own personal opinion and I respect everyone who has greater skills and knowledge than I do.

On a different note, the OP in that thread has his unit powered up and on the bench - have you tried reaching out to him and asking how he has achieved that? Did he just connect 12V and Ground or did he have to futz with the canbus connectors too?

ZedZed

Something I didn't know until reviewing @andy2111 's post above was that Erisin have a UK website: https://www.erisin.co.uk/

Members in the UK and EU might be interested.

andy2111

That's a good idea.. I'll ping him a message. Will still do the DOA test to make sure its not bricked already

I noticed on one of the rear plug in connectors there are 12v, wake and other wires.. I think these are voltage outputs rather than alternative ways to power the HU? I think I read they are used to power accessories?
​​​

ZedZed

Yes, you are correct - they are used to power accessories, cameras, antennas etc.

It's really odd why your unit didn't power up when you connected 12V to those connectors (and ground). If you get to the bottom of it, I'd be really interested to understand more about this. By coincidence, I was going to bench power the unit in my wife's Cayman so that I could set it all up from the comfort of my desk, but in the end, I just took the plunge and installed it. Because I had already installed three other, similar, units before the Cayman, I figured it wouldn't take me long to configure that unit. Turned out I was right in the end. Sounds like I may have dodged a bullet there.

GermanCarFan1

What are some of the low profile ( not big and bulky) back up cameras to install that have good resolution and the lane articulation lines that are accurate...?

I've seen many, but want to know which is the best without spending too much coin..$100-150

Any feedback? Thanks.

ZedZed

This is the one I have installed on two different cars and I have had no problems at all. I installed one over a year ago and it is still working just fine. It looks OEM when fitted, supports guide lines if required, gives good night time image, comes with all wiring and clear instructions. It is a good quality camera made of metal (not plastic) and if I needed to install a camera on yet another car, I would buy this one again.






There are cheaper cameras available, but I have been very impressed with this one.