New SI Board - still no Tach or Speedo?

[blasphemy101]

Like the title says, after installing a new SI board (along with testing several other clusters/gauges/SI boards). My Speedometer, Tachometer, and Current MPG gauges (always reads 40mpg) still don't seem to be working.

Here's a slightly interesting detail: If I turn the key to ON (not starting the car), the fuel and temp gauges move to their appropriate positions. The Tach and MPG gauge needs, however, flick like they're about to start moving. If I turn the key back to OFF, the Tach needle will glide up to 1000-1500 RPM and then move back down. If I try turning the key back to ON shortly after turning it on the first time, the needles will not flick.

After installing the board, do the batteries need time to charge? It is a 13/5 Pin board with the stubby batteries. My car is a 1987 325is.

Thanks!
- James

[UPDATE] I used my multimeter to go through the ground check procedure outlined in the Bentley manual. Everything checked out.

However, looking under the steering column, I found these disconnected. They're both female. Any ideas what they plug into and if it could cause my problem?



[EDIT] I almost forgot -the wires on the left are: red/white, brown/blue, and brown. The wires to the right are red/green, green/brown(?), and brown(?) going from memory and the picture, sorry. The colors of the disconnected wires appear to correspond with some of the connectors on the back of the instrument cluster.

[MoreMayhem]

Those are for the chime module that would normally be mounted to the under dash trim panel. Probably unrelated to your cluster problems.

-MM

[blasphemy101]

Thanks for the response. While I was working on the car, I was actually wondering if there was supposed to be some sort of chime going off while the door was ajar :D

[blasphemy101]

I found a small amount of resistance to the main ground for the instrument cluster. Could this be the cause of the problem? I plan on checking the ground again with fresh batteries in my multimeter.

[nando]

are you sure your diff sensor is working and connected? the speedometer does't need the SI board. the MPG gauge doesn't need the tach to work, although they share a connector they're wired independently. both rely on the SI board, and the MPG gauge of course needs the speedo to work.

[blasphemy101]

I've checked the sensor on the diff, and it appears to be fine. That said, it's 25 years old, so I won't rule it out entirely.

When I get home today, I plan to check on the ground again, because of that small amount of resistance. It was present on the main ground for the blue connector but not the white one. I traced some of the runs on the PCB, and it looks like the blue plug has connections to the tach and speedo...