Tach does not work ????

What could be wrong? engine out service just complete and check engine light 1-4 is on as well. Any ideas?

 

Check the connections on the alternator. Make sure that the little green plug, on the back, is all the way in, and that the wires are in good shape. Then make sure that ALL of your grounds are hooked up properly. If it is still giving you grief then pull the instrument pod and have a look at the connector on the back of the tach.

 

i will try it out thanks

 

Is it possible (???) that you have the 1/4 and 5/8 crank sensors plugged in at reversed positions, or unplugged?

The signal for the tach is supposed to come from the 5/8 Motronic unit, according to the manual. Something must be wrong in that area if you haven't been messing around with the instrument cluster.

Is the phase sensor on the back of the 1/4 head plugged in?

 

I never unplugged them. Some coolant ran down the front of the engine and might have gotten in the terminal but I doubt it.
Where is this located??

 

How could the engine be removed without unplugging the crank sensors? The parts book says that the two sensors are the same part number, so I assume they have the same plug, so it must be possible to plug in the 1/4 sensor so that its signal is going to the 5/8 Motronic unit, and vice versa, which would throw the readings out of synch, which MAY cause the tachometer to malfunction. I'm totally guessing. If the tach worked OK before the service, and it doesn't work now, it seems like there should be a simple explanation.

Edit: OK, you can remove the engine without unplugging the crank sensors. But it's still possible to plug the sensors in backwards, isn't it? On page C9 of the manual it warns against plugging them in backwards.

 

If one crank sensor does not work properly the engine will only run on one bank. The reason is the fuel pump does not work if the sensor does not work. At least that was what happened to me a few months ago.

//B//

The manual you are referring to ..............where can we find such a one?

 

I cleaned out the sensors and still no luck. It's only running on 4 cylinders.

 

Just for kicks, try unplugging the cat ecu on the side that is not running. Then if that doesn't work, swap the crank sensors from one bank to the other and see if the problem switches sides.

I would suggest pulling the codes, but if you pull the codes with the engine off you will always get one for the crank sensors. You could try turning the engine on and pulling the codes, but I don't like the idea of the engine running on only half a bank while you are try to get the codes out. So that is why I suggest swapping the sensors from to bank to the other.


Also, did you check your grounds????? A poorly grounded car will give you all kinds of weird problems. Ask me how I know.

 

To recap, you've got 2 problems:
#1, your tach isn't working and
#2, your engine is running on 4 cyls.

If the same fault is causing both problems (likely), then you are looking at two things: crank sensor for 5/8 or engine computer for 5/8.

The most common problem is with the black cable that connects the crank sensor. Pull back the black rubber cover behind the cable connection. You could easily find a loose wire there (just 4 wires/pins/connections there if I remember from the last time I did that check on my car).

If the pins/connections are fine on the cable, then you can either install a new crank sensor or else swap the 1/4 crank sensor with the 5/8 crank sensor (same part).

If one crank sensor was bad, then the running engine bank would switch sides, and if the problem was the 5/8 sensor, then switching crank sensors would fix your tach, too.

If swapping crank sensors fails to change anything, then I'd suggest swapping engine ecus. They are behind your car seats and simply unscrew. They are identical. Move them from left side to right side and vice versa.

If you have a bad engine ecu, then I can give you a simple test and potential fix.

 

The problem was a blown fuse behind the driver seat. It is right next to the ecu code button on the drivers side.

 

There's a fuse back there?!

 

There's a fuse back there?

 

Well thats a new one!?

 

Jesus just when u think u know about these cars, this sheit has to happen! Am adding this to my "Where extra fuses and relays are that are not in the place where they are supposed to be" DB.

 

Okay.

"WHATCHU TALKIN BOUT WILLIS?!"

I just when out to my car and looked at both ecu's, and there are NO fuses back there. I even pulled up the carpet, around the ecu's, and I still didn't find any fuses back there. My guess is that you have some sort of an after market alarm hooked up to your car, and they spliced into the wiring to the ecu's, for who knows what? Maybe to kill the engine if it goes off?

 

AAAAGH!


[ INSERT LOUD SCREAM HERE ]

 

here is the pic of the fuse.
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Well, just so that I know I'm not crazy I went to the garage and looked again. Not fuse or relay like that in my car.

 

Must be something that was changed on very late 348's? I've never heard of a relay/fuse like that next to the Motronic.

Down at the bottom of that picture, there appears to be a gold-colored box with a white paper label on it. My car doesn't have that either. Can you tell us what it says on that box? I'm wondering.... there have been a few people who have mentioned a "buzzing" noise coming from behind the seats under some conditions. Could it be that the gold box is a warning buzzer? Or possibly something to do with the circuitry exclusive to the Spider? I don't have a wiring diagram for the Spider, so this is a mystery to me.

Edit: I'll bet that box is part of the seat belt system.

 

That's what it looks like to me. It's a motor for opening/closing something, and as you sad it's probably for the stupid mad mouses. But what is that relay and fuse for????? An why is that connector unplugged (the blue one)?

 

I just snapped this shot of my 1994 348 Spider's 5/8 ECU area. Notice that my 5/8 ECU has a black plastic wire connection in addition to the normal ECU wiring harness connector.

On my car, that black plastic connection is direct, but you could easily have a fuse spliced into that point...perhaps that was done on 1995 348's by the factory itself.
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Anyone else with a 95 spider have the same as mine?

 

FWIW
Tried looking at the wiring diagrams, and can find differences on euro vs can vs us, but not very clear on US @ '95. But does show some differences in wiring and parts for the 2.7 Motronics in that area...but minor.

prob. just a late release change: BTW, my Mondial T has TONS of fuses, relays etc. in the Trunk....bugger to trace out.