I ordered a new TACH using the # from the PET and confirmed with dealer. However, when it came and I removed the old unit, there is a clear difference. My original unit does not have an upshift light, and the newer does. The one in my car has 3 lugs, the new unit about 6 more.

Not sure how to proceed. All the cross references says this is the right part for a 1989 944 S2 (US), but it is clearly not the same.

Do I install this and leave the new lugs unconnected? Or do I buy nuts and washers and connect everything?

Also interesting on my gauge cluster, there are 3 light holes that have no bulb. When I shine a light in the holes, it says 'check engine'. I thought this car just had the big '!' as the universal warning light.


current on left, new (with upshift light) on the right.

Current tach with simple electronics

New with more electronics and lugs

current tach on left, new on right. Can I bolt in the new and use new nuts and washers to attach? Or will I burn something out?

New Label from when the part was likely restocked.

Box showing the 'correct' part number. Talk about NOS...... Was made in 1989.

check engine icon illuminated with flashlight

unused light sockets

Any advice from the group? Will comment on each pic.

 

The new one looks kinda like a 968 tach, although I'm not sure if there is a spot for an upshift lamp in my 968 and my redline starts at 6600.

 

I noticed the higher redline as well.

My main question is what to do with the 4 extra lugs. Do I put a nut on them? Will it mess up the DME? Or should I just connect the original 3 and ensure the 4 extra lugs do not touch the ribbon?

 

The 89-91 PET calls for 944 641 952 08, or 944 641 952 10 if your car has a shift indicator (manual US cars should have this.) Not sure what references you were using.

(Also -12 for automatic, -01 for turbo)

 

Yes, I used the PET and it lists those numbers. Problem is when I checked that part with my VIN, every Porsche dealer said it was not compatible. On every Porsche Dealer site, the 944 641 952 10 says it is not for my car, but the 944 641 952 11 was. Oh well, it is in, looks great and most importantly works!

 

Hook it up using the 3 lugs used on the S2 and see if it works. If not, then youll need to send it back and get a correct tach. Im fairly certain it will though.

FWIW when my S2 tach went bad, I put a used one in from a 8V NA oval dash car and it worked fine. The MPG gauge didnt work, but who cares (I actually used the faceplate from the old S2 tach so you wouldnt notice any difference). Yes the redlines are different but only slightly (and the S2 doesnt make power over 5800 RPM anyways so no need to really ever rev it to redline). I would bet it will work if hooked up using the 3 prongs. Ignore the bulbs. Ignore the upshift indicator.

If you really want it to match, you can gently pry off the tach needle (gentle prying with a fork works well) and swap the faceplates. Then your redline and everything will line up. Install the needles carefully and dont bend the shaft they ride on.

PS - Not sure where you are cross-referencing that part number as a S2 tach, but when I run it it comes back as a tachometer for a 87-88 944 S (2.5L 16V engine) so very similar to the S2 with just a slighly higher redline (Source).

 

Best I have been able to google around, the tach you received is for an 87 on S model. It is listed in the 85-88 PET.

 

Sweet...new tach got you 250 more revs before red line...I say it is a win <jk>

 

I bolted it in and it works perfectly, and 'thankfully' the DME does NOT light the upshift light. Thanks for the input!

 

What??? It's an awesome feature. If you only knew (i.e. read the owners manual.)

 

I could be wrong but I read it as 400 more RPM! 6400 vs 6800!
Nice job!