[dc8dude]

I did a search for this and found no similar threads so here is my dilema - I swapped in '98 drvetrain in my '88 YJ and had it set up with the cable driven speedo and the old tach hooked up to the coil driver - it all worked fine until my speedo went out so I decided to put in the gauge cluster out of a '95 YJ I had sitting around( I also wanted to get the VSS hooked into the PCM). I hooked it all up using the wiring diagrams(3 different models!) and have gotten everything working well except for the tach which reads about 30% high hooked up to the coil driver. I know the '95 had a tach output on the PCM while the '98 just has the single CCD bus wire for the entire gauge cluster and I know hooking it to the coil like the old days doesn't work so I'm about out of ideas. Anybody got any suggestions(other than putting all the old stuff back in!)?

 

[MossMan]

I think you need a tach from a 4 cyl.

 

[witz]

I know when you put the Mopar EFI kit on an earlier YJ, they tell you to buy a new tach because it uses a different voltage range. I suspect that this is an equivalent issue. Just change the tach to the correct one.

 

[dc8dude]

I figured it out!

Just thought I would post my solution to this problem in case anyone else runs into a similar problem. I left the the tach signal wire hooked to the gray coildriver wire. Like you said it was reading for a 4 cylinder engine but since I have heard these electronic tachs work on both the 4.0 & 2.5 engines I decided to take out the tach and have a look see. On the top of the circuit board I found a tiny blue electronic thingamajig(labeled 103) with a tiny adjustment screw. I found that by turning this counterclockwise I was able to adjust the resistance(or whatever) to give me the proper reading(I had a tach meter hooked up). So I guess they really do work for both engines, you just have to adjust them!

 

[Knoxville]

Nice! I have a '98 drivetrain in an '89 YJ. I am using the mechanical speedo with the tach hooked up to the coil driver. Could you post your wiring connections for hooking up the '95 YJ cluster?

 

[dc8dude]

Hey, no problem. The only things I have connected on the cluster are the speedo, tach, turn signals, and parking brake light. On the '95 anyway I think they have the 4WD light over on the other instrument cluster so I haven't hooked that up to any light nor do I care to, ditto the MIL light. I got the gauge cluster off e-bay awhile back and found a under dash wiring harness off a '95 in a junk yard so I would have the plug which goes into the back of the tach. The cluster itself will fit right into your YJ but you will have to cut out the idiot light portion of your dash bezel as they are already on the instrument cluster. The best bet is to get a wiring diagram for the year cluster you are putting on but you could always just go through the pins on the back with 12V to see which wire does which light. You already have the tach connected the way I do(to the coill driver) and you can adjust it as neccessary as described above. You can use the VSS out of a '98 and it will work fine on those speedos. Just splice into the white/orange wire running from the VSS to pin B27 on the PCM and your in business. Having a VSS connected to the PCM does improve the engine's response at very low RPMs.I've got tons of wiring diagrams if you need.