funny speedo and tach

scott91gtz · Post by **scott91gtz** » Sat Oct 27, 2007 12:44 pm

i have a 91 gtz. lately my speedo and tach have been acting up. both are jumping all over the place, usually reading way higher than they should. for example ill be driving along at 95 km/hr and all of a sudden it will jump up to 150 or so, and the tack will jump from 2500 rpm to 4000. and often when im at a set of lights it will still read 40 km/hr and 3000 rpm. it seems to happen mostly after the car has warmed up (???) and every time i switch on the rear defrost. i did hit a racoon about a day before i noticed this happening, although im not sure if this is related at all, and for the last week or two i have occasionally noticed what smells like melting plastic.
i have a feeling sumthing is shorting out im my dash, and that im gonna have to pull it apart and take a look. im just wondering if anyone else has had this happen to them before, or if anyone can give me some direction as to where exactly to start.
your help is appreciated
scott

scott91gtz · Post by **scott91gtz** » Sat Oct 27, 2007 12:50 pm

i forgot to mention that all the rest of my guages work properly as far as i can tell. fuel, battery, oil pressure, and temp all seem to be the same as before. i dont know if this helps at all, but i figured id mention it anyways

Money pit Beretta · Post by **Money pit Beretta** » Sat Oct 27, 2007 2:03 pm

After you check the wires get back to us and tell us what you came up with. Is your car running ok?

scott91gtz · Post by **scott91gtz** » Sat Oct 27, 2007 4:33 pm

i havent had time to open it up yet but i did just notice that when i put on my signals it jumps around too. im starting to get the impression that there def is an electrical problem in the dash sumwhere.
also my car isnt running 100% right now. every now and then it seems to stumble, has no power and sucks back the fuel. i pulled apart my injector harness and that seemed to really help. it rarely does it now and if it does, its only when its cold.

Money pit Beretta · Post by **Money pit Beretta** » Sun Oct 28, 2007 2:23 am

My turn signal drops the volts also, but there is nothing wrong with that(on the gauge). Do the heater and AC controls work ok? Does it start up right? No codes?

1988GTU · Post by **1988GTU** » Sun Oct 28, 2007 2:30 am

Check the wires to the crank sensor and make sure the ECM is not corroded on any of the pins to the connector. After than, make sure the alt is putting out the correct voltage and your battery is good.

Post by **Cliff8928** » Sun Oct 28, 2007 2:54 am

Yeah, I remember my old '89 that had analog did that when the alternator went out.

scott91gtz · Post by **scott91gtz** » Thu Nov 01, 2007 6:32 pm

i wont be able to look at it untill saturday, but thanks for the tips so far. i have the ac disconected, but the heater seems to be working fine although it doesnt blow very hard, but it never has.
as for codes, the light isnt on, and when i plug in the scanner, the only thing that it reads is the code for the AC.
i have replaced the ECM with another onea while back, to see if that would fix the stumble, but it didnt change anything, so i replaced it with the original again, b/c the one that i got was out of an automatic... (speedo way out and stupid shift light came on always).
i will however pull it out again and double check it, and the plugs to be sure its OK and ill check the crank wires, the battery and the alternator, although the alternator was just replaced about 4-5 months ago.
i have also noticed that the volts are reading lower than normal (prob around 12 rather than 14ish) so im thinking that either the alternator isnt working properly, or perhaps i have a bad ground somewhere, which could explain all of the problems im having.... looks like i got some diggin to do.... an i HATE doing electical lol.
thanks again for the help and ill keep u updated
scott

scott91gtz · Post by **scott91gtz** » Sat Nov 03, 2007 4:17 pm

k so i got under the hood today, and i found out that the noise that i thought was the powersteering is actually the alternator. it seems that a bearing is shot on it. right now its putting out about 12.5 volts, but i dont think its gonna last too much longer. i disconnected my amp, to take a bit of pressure off of it so that maybe it will last me untill next week when i can finally replace it. hopefully that is the source of my tach and speedo issues too.

Money pit Beretta · Post by **Money pit Beretta** » Mon Nov 12, 2007 10:10 pm

Did you get the work done?

scott91gtz · Post by **scott91gtz** » Tue Nov 13, 2007 6:45 pm

ya it did. sorry for the delay... ive been busy lately. but since i got the new alternator in, everything seems to be cleared up. actually what happened with my old alternator is of the 3 bolts that hold the back onto the front, only one was left, and it was already half out... the alternator was almost ready to fall in half!! but ya its running good now, i just gotta replace that belt cuz its pretty worn. but thats coming in 2morrow i beleive. anyways thanks alot for all your help. its greatly appreciated.
scott

Money pit Beretta · Post by **Money pit Beretta** » Tue Nov 13, 2007 6:55 pm

Good to hear,man. Did the bolts just fall out or break? Do you need torque specs?

scott91gtz · Post by **scott91gtz** » Wed Nov 14, 2007 6:03 pm

no by the looks of it the bolts just worked themselves loose. it was really wierd... i've never seen anything like that b4. i figured i wouldnt have to check the specs on it, b/c it was completely assembled when i bought it... pulley and all. so ya either that alternator's shaking like crazy... which i'm pretty sure it isnt... or whoever rebuilt it did a **** job.

Money pit Beretta · Post by **Money pit Beretta** » Wed Nov 14, 2007 10:33 pm

That's why I try to buy GM of better stuff for my car. Or was it GM? I hear they may not make them in the US these days.

scott91gtz · Post by **scott91gtz** » Thu Nov 15, 2007 6:21 pm

no it was a "champion"... i know not to get that anymore. this time tho, i managed to get a delphi.... which shuld be much better, and i got a 115 amp right away

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