StevenK

I think one of my next biggest things from keep my car road worthy is the speed-o, tach, and oil pressure (not that big of a deal) are not working at all.

I have a pillar gauge for the oil pressure, so that is ok for now, but I need to fix the speed-o and tach for sure.

We checked the wires on the ECM and there was a signal there, we then traced the wire into the cab where the harness connected and found signal there, we then moved down to the back of the gauge cluster and found signal there as well, but for some reason, nothing shows up on the gauge itself.

The 91 145mph cluster worked perfectly fine with the L98 before the swap, teh RPMs were accurate and the speed worked all the way up to 145.

When I plug in HPTuners scanner it sees the RPM and speed there just fine, so the ECM is getting it, but the dash isnt.

I've heard you have to change the tach value or something in HPTuners to get an accurate readout, but I should be at least getting something right?

Any insight is appriciate, thanks.
-StevenK
ps forgot to mention that the dash fuel gauge and battery gauge work perfectly fine, and when we hook up the temp sensor wire on the harness to a signal the needle pegs out, so that works too (just need to put a thirdgen sender on it and put it in a extra port.)

StevenK

I was just thinking, is it maybe that the signal wires coming from the ECM are designed for the 4th gen dash, which I understood uses one serial connection? Am I supposed to be getting the signal directly from the VSS and a crank sensor or something, or am I supposed to be using the wires coming from the ECM to the 4th gen dash?

Hmmm, perhaps I should take out my cluster and put in a little screen and run a program to run the gauges off the ECM like HP Tuners does

2K2WS6TA

iTrader: (2)

Have you looked over at www.thirdgen.org they have a pretty extensive section that covers LS/LT1 swaps in the engine swap section, including what to do with the gauges to get them to work right

G-Body

iTrader: (4)

The speedometer signal from the PCM is not a serial data signal, it should work fine with any electronic GM speedo, it is a 4000ppm square wave DC signal.

The tach signal that you are using is coming from the PCM red connector pin 10 right? If it is that is actually a signal for the stock traction control or ABS I think so it is not a serial data signal. It is normally a 2 pulse per revolution signal which is a 4cyl tach output, you have to change it in the PCM to get it to be the correct 8cyl signal but I don`t know exactly how to do that.

MrDude_1

iTrader: (4)

the VSS out signal from the PCM works perfectly with your speedo.. just plug and play.

hook the tach output directly to the tach, and then get someone with HPtuners or EFI live to change the tach output.. its just two numbers that have to change, no biggie.. i'll post em if you need em, but i dont have them on this pc at the moment.

for watertemp, screw in a sensor to the passenger side head, and hook that up to the gauge wire... im using a 98 camaro temp sensor.. its not accurate to the stock gauge backing, but perfect for the stock thermostat to the LS1... aka, straight up when its warmed up... you can also use a diffrent sending unit to match... theres dozens of ways to do it..

StevenK

Hmm, I thought the tach wire was white.....I think it was PIN 10....

I got HPTuners, but I didnt really see the place to change the Tach to 4cyl mode, if you could post directions on that I would appriciate it.

For the water temp I was going to screw in a thirdgen sender, should I not do that? Like I said earlier temp isnt too big of a deal right now, I just want the tach and speed-o to work.

Its really weird that my gauge isnt getting anything at all, I figured it would be off, but still work....I wonder if somehow my cluster went bad while the car was sitting.

Is there anyway to test the cluster, or the signal?

MrDude_1

iTrader: (4)

tach wire on 99 to 2002 fbody harnesses is white #10.




in the Engine-> General window of HPtuners, theres a Tach output area on the right. change both numbers to 3 for a V8 signal...
im looking for the formula again to calculate it out, but it can send a 6cyl signal too... your choice.
see attached pic:


you can do that just fine.
as long as the green coolent temp signal wire is hooked up to a sensor, it'll show some temp reading.. its a GM standard gauge in the dash, so its range works with most things.


what gauge isnt moving at all? there is a gauge fuse for all of them.. then theres the signal wires.. if you have the voltmeter working, they're getting power.. you probly just have one of the signal wires connected wrong....
for the speedo make sure you're hooking the VSS signal directly to the gauge.. not to the stock thirdgen harness with its buffer box and such...

StevenK

Ok, I'll check to make sure my Speed-o is connected directly to the VSS on the tailshaft and make a pigtail from the ECM to the dash and check to see if Something is miswired in the loom.

In HPTuners the ECM was already set to 3 on those values, so just leave it at 3?

MrDude_1

iTrader: (4)

no.
NOT to the tailshaft VSS SENSOR but to the VSS OUTPUT from the PCM...

its white 220 plug, pin K
DK GRN/WHT wire
PCM pin 50


then its set for V8 tach output already.

StevenK

I went to install the temp sensor last weekend, and found out the 3rd gen sensor is muuuch bigger than the hole in the passenger side of the head.

I did a little digging and found out the hole in the head is a 12mm x 1.5 thread, what is the stock thirdgen temp sensor? Also, space is pretty tight back there, is there anyway to put an elbow on it? If so, would it be better to get a 12mm x 1.5 elbow, or an elbow that fits the 3rd gen sender?

I'm really wishing I had done this before putting the motor in, the passenger side of thirdgens is always a PITA.

G-Body

iTrader: (4)

Yep the third gen sender is probably the same 3/8" pip thread as mine was. I cheated I had my uncle chuck it in a lathe and cut it down to 13mm then I used a standard metric die to thread it 12mm x 1.50 . If you can`t find anyone with a lathe you could probably chuck it in a drill and use a file, that is what I would have done if my uncle hadn`t stopped by. I used an aluminum washer from an extra metric/american adapter to seal against the head.

I attached a pic of the rethreaded sender

StevenK

Dude, that is freaking awesome. Any chance he would do one for me? I'd be willing to pay for it.

I was just thinking about the whole adapter thing.....its a stupid idea and will never work. The sensor has the long unthreaded section which would never fit into the adapter, the center of the adapter would have to be pretty big. Not to mention it would move it outside of the flow of coolent which would probably make it show colder than the coolent really is.

I was talking to one of the car guys at Autozone today that has always been helpfull and he suggested maybe I get an Autometer sending unit, but I'm not sure if it would send the correct signal.

Just how much off is the stock 4th gen sender if you hook it up to the thirdgen dash? Would it be close enough I could just memorize a new spot on my dash as the red line?

MrDude_1

iTrader: (4)

with the 4thgen sensor:
the redline is still the redline.
straight up is still normal operating temp.

StevenK

I saw in another thread that it is not acceptable to slice into the stock sender on the driver's side head, but it didn't state why. Anyone care to explain that?

If thats the case, I'm just going to put another stock sender in it, I dont know how I didn't find that info, I suck at the search.

Once again, MrDude to the rescue, you need a medal or something.

G-Body

iTrader: (4)

You can and can`t splice into the stock sender in the drivers head. If you have the 99 or newer 2 wire sender you can`t splice into it since its output is a serial data signal for the computer. The 98 had a 3 wire sender that had a serial data output for the computer AND a standard resistance output to go directly to the gauge. If you have a 98 motor just hook the dark green wire to you gauge and your done. Or if you have a newer motor you can retrofit a 98 sender, either put the sender in the passengers side head and ground the brown wire, hook the dark green to the gauge and disregard the yellow, or put the sender in the drivers head, hook the yellow wire to the yellow wire (pin 74 of the blue pcm connector) , hook the brown wire to the other wire (color varies by year but should go to blue PCM connector pin 80) and then the green wire to te gauge

StevenK

Man I dont know how I want to do this now.

How do I wire into the 2nd stock sender? I don't have a spare connector to use. Do I just solder the wire directly into the female connector on the sensor?

Same thing with using a 98 sensor, that sounds like it would be the best way to go and just replace the 00 connector on the driver's head and use a 98 sensor so I can hook the third wire to the dash. But where can you buy a 98 connector for the harness / dash connection?

G-Body

iTrader: (4)

You will need a 98 three wire sender either way. Even if you put a second 2000 sender in the passenger side head you cannot hook the gauge to it since it would be the wrong signal.

For a connector I would go to a GM dealer, any chevy dealer should be able to get one if they don`t stock it. Just tell them you need a new connector and pins for a 1998 camaro coolant temperature sender.

StevenK

Bah, I hate the Stealership :-(

But I want a working car, so stealership it is. I'll just replace my current 00 sensor in the driver's head and replace with the 98 sensor, and cut off the 2000 connector and wire in the 98 connector and put the 3rd gen signal wire on.

Thanks for the info guys, MrDude and G-Body you guys rock.

MrDude_1

iTrader: (4)

noo.
leave that sensor alone
put the 98 sensor in the PASSENGER side head... and hook it to the 3rdgen gauge and ground.

the 99-02 sensor is for the 99-02 computer.. the 98 one has a slightly diffrent curve to it.

jtmiller92

iTrader: (74)

I used this method as well, i was alittle more crude when doing it though. I used my benchgrinder to grind it down small enough that the 12mmx1.5 die would cut it down the rest of the way. It worked out great the second time. Its easy to cut down. Only reason i messed up the first one is because it was tapered and larger toward the head so as i cut it with the die it got to tight and broke the end off. Second one was easy to do and guage works great. I still have to get my speedo working too but everything else works..................jt