3800sc swap wiring gauges issue

I have completed my swap of a 3800sc into my kit car, it starts and runs purrfect!, however it has VDO gauges and they all worked fine before the swap, but now the oil pressure guage and temp pin max when key is in on position, start the motor, the tach comes on for about 3 seconds and drops out, the temp gauge goes back down but the oil pressure gauge stays pinned.. no speedo either..all these worked b/4 nothing up under the dash was changed...could this issue be at the c203 or c500, or the ECM any help would be appreciated D.

3800SC engine has much higher oil pressure so this is common and there were two different 88 oil pressure sensors so getting the other might help.
Gauges pinning when key first on is factory and can be dealt with. The Tach sounds strange and the speedo should still be working unless the speedo buffer is needed. Which tranny are you using. Dan

Is your engine Series II or Series III? With a 3800 SC Series III engine, computer from a 2006 GTP, and VDO instrumentation, there are a couple of potential issues that I found. The computer tach signal will not drive the VDO instrument. The only two solutions considered to date are either a new ignition systems with a tach output or rebuilding the alternator to include a tach signal from that component. No ignition systems with a tach output that work on 3800 SCs was located so I used a pulse modification on the old alternator to drive the tach.

The other two issues discovered were resolved by a tee in the oil pressure line for the VDO sensor and a new tap for the VDO temperature instrumentation. It would be a much better solution if the two oil and water pressure measurement points were done prior to engine installation and integrated into the harness. I have never experienced the instrumentation pegging problem that you referenced but the oil pressure is around 70-80 psig on the Series III engine so your sensor must include the correct range. To calibrate my VDO speedometer I used a GPS and the initial set was within two miles per hour. Then you can use the VDO incremental trim process to match the GPS and speedometer. No additional buffer was needed for the speedometer.

Nelson

[This message has been edited by hnthomps (edited 04-19-2014).]