six2eight

iTrader: (3)

RESOLVED! gauge works!

Here are the basics and final product.... I have a 98 car with a 98 fuel sending unit and a 99 LS1, 99 engine harness, and 99 PCM. I sent the PCM out to Frost to get the PCM set up to read properly for the 98 sending unit out of the 99 PCM. However, something is still not working properly.

I have tried searching to no avail.

I know the typical PCM swap involves repinning the connectors on the PCM and retaining the 98 harnesses. However, on this swap the body harnesses are the only 98 items left. as such, I repinned the plugs behind the passenger side kick panel to get the gauges working. By the way the gauge is showing full all the time

I am assuming I have on of two issues... the sending unit is messed up and not working. Is there a way to test this?

The more likely option, I am missing a wire or put a wire in the wrong pin slot. I noted on the 98 dash harness there are two fuel gauge sensor signal wires in the C210 wire however, there is only one in the 99 engine harness. as an additional caveat, I deleted the evap system so thats not critical that those wires are correct to the extent that they do not affect this.

I would greatly appreciate any help, I know someone on here has done a full 99 swap into a 98 car and retained full functionality. This little gremlin is driving me crazy!

sicksspeed

iTrader: (2)

Reading full means open circuit. If you know the circuit you can measure the resistance. The sending unit will read low resistance empty high resistance full. Exact numbers I would have to look up.

Ed Wright

iTrader: (1)

I have to wonder, what is the perceived advantage to a '99 PCM?

six2eight

iTrader: (3)

it was originally a v6 car and a 99 LS1 was the most available part source for me. the fact that its originally a v6 should be irrelevant to the fuel gauge functioning because I had a 98 Z28 cluster in the car with full functionality right prior to the swap.

six2eight

iTrader: (3)

I finally got this fixed and this is great info for anyone putting a complete 99+ LS1 PCM and wiring harness into a 98 body car.

The typical 98 to 99 pcm swap entails repinning the 98 engine harness to match the 99+ PCM. However, in my case I had also utilized the 99 engine harness. I was not getting gas gauge functionality because the 99+ engine harness does not have a wire that runs out of the Red C2-38 pin. Typically you would need to move the DK BLUE wire for the fuel gauge level to this spot using this (98)Red C1-36 DK BLU TO (99+) Red C2-38.

To resolve this and gain functionality you will need to have the PCM programmed with the segment swap that is discussed in other threads. AND add a wire to the Red C2-38 pin assignment which will need to be run to the C210 E behind the passenger side kick panel.

you can either hard wire a new wire, or in my case I deleted the evap system on the car so I utilized an existing wire to and repinned it. I think it was Red C2-64 dk green that I moved to the Red C2-38 spot. and then pulled it from C210 F and moved it to C210 E.

Hopefully I got all these numbers correct as I am doing it from memory, but the basic story is that it's really simple to drop a complete 99+ in a 98 car and retain full functionality of the 98 gauge cluster. Any questions hit me up.

RedEvilz28

Is it a way to get the gauges working without having to take the 99 out an getting your 98 repined

taws6ali

I am currently having the same exact problem... bought a roller with. 01 pcm on it and due the the way they have the 2 visibal wires ran directly to the pass side 3plugs (one from harness the other fron pass side fender plugs) it seems like the original owner used a 99+ harness *** well... he tellls me everything worked when he had his motor as far as guages. I installed a 99+ fuel sender and tank had frost do the tunning and segment swap. The guy at frost said i need to add a direct wire to my cluster. If you can get me an accurate color and pin location to repin fuel guage to get it to work with my 99 sender. and do you know wether the guage cluster wires needed repinning while the previous owner was using 98 sender? Im a newb at this and need all the help i can get thanks bud

taws6ali

Can I get a 98 clash cluster to work with a reppined 98 engine harness, 01 pcm and 99+ fuel tank and get functionality of my fuel gauge ?tuned by frost did a great job with the tune, changed my tank size and put in a 99+ seg swap (since previous owner had another one due to the 98 style tank)
mall my other gauges work just fine. Do I have to put in a 99+ dash cluster and harness ? Or is there a way to keep my original miles since I'm the sec owner of this vehicle with 40k miles on it. Thanks

spaz1

iTrader: (9)

All the gauges worked ok for me as long as they did the fuel gauge segment swap.and use the 98 sensors. The 98 cluster is still analog. I was running an automatic. I converted mine. You won’t hav to worry about that. Was just for the park neutral and reverse.
I labeled every wire and reused my connectors. Turned out really messy. Good idea with another set of connectors. You will need to extend a some of the wires.
I would prob just label the new locations on the wires before you start pulling them out.