So i just bought a 91 RS 305 TBI 5 speed car and like many that have been looking for clues, I am here also looking for clues. I must say this is one of the most informational websites I have ever been to on the web. Now for the problem.(s) When I bought the car someone was nice enough to go in and hack the wiring up and then sell it. I have used many of the schematics from this site and the Austin site to scape together a good representation of the electrical in the car.

My car has an issue with the gauges amongst other things. The oil pressure ,fuel,temperature, speedometer, tachometer gauges do not operate. After a couple weeks of probing the car I believe i have narrowed the problem down to a bad ground wire on the C2(left)(drivers) side of the instrument cluster. The information I am looking for is the location of the S217 grounding point that the gauge panel uses to make its measurements referenced to. When measuring "all" the lines coming into the gauge cluster they are all present as shown on the DMM/Freq (referenced to the ground from C1(right)(passenger). This is a good sign as the signal lines are all present but the gauge will not operate without a good ground. There is no continuity between the ground on the C1 and the C2 side(voltage present).

Any help is greatly appreciated.

Thanks,
Mike

 

First off, welcome to tgo. There's alot of great info and people on this site that are willing to help out. Now for your problem. S217 is a splice in the harness. Thats what the S stands for. If it were a grounding point, it would start with a G. Since you've located that you have a ground problem and after I studied the wiring diagram for you car, I would look at the ground connection G118 at the rear of the cylinder head on the pass. side. Thats where the ground is located for the gauges. S217 is the splice in the ground wire for the G118 grounding point. The splice and ground is for the tach, speedo, fuel and oil pressure gauges. The temp and volt gauge is on a different grounding point G200 which is located under the dash, right side of the steering column on the covenience center mounting bracket. If the volt gauge works, I would suspect the temp gauge sending unit wire is disconnected at the sending unit in between #1 and #3 spark plugs. Hope this helps.

 

Just reading this I finally found out what G118 and G200 are in my diagrams and where they are located. Thanks jermdm

 

Thanks jermdm for the very quick reply. I'm sure this bit of information will help many in the future. Had I known the symbols from the start we may not have met !!!!!

Keep up the great site. Now lets go racing !!!!

Mike
Tucson Az.

 

We would love to have pictures Mod9.

 

I'll be out there working on the problem again today. Ill either get some video or pics so that everyone can see the symptom and the fix. I do know the previous owners tried the heater delete which i have now put back in. I believe they were messing around the back of the block and looking at their handy work I believe they have broken the wire off and did not even realize it. Best first guess however. I believe my goal is to return the car back to its original electrical configuration. Ill tackle the electrical problems one at a time unless I find one problem fixes everything... not likely as my VSS sensor signal appears to be weak or bad. That's the next problem. Stay tooned (yes spelled correctly)

Mike
Tucson

 

Well as promised here is a video of part of my gauge check-out.

 

Here is the fuel gauge check. If you want more detail just ask. I can always set this up again.