I am reaching out to all you electrical gurus for help. I can’t think of anything else to try.
I have a Speedhut digital boost (only) gauge in my 86. It came with the car when I bought it. It worked fine for years. This Spring I made some changes including the installation of an AEM A/F gauge, changed to an LT-1 MAF with translator and added a powerlogger which also upgraded my scanmaster to 2.2.
At about that time, or soon after, my boost gauge started acting up. It went through some weird phases but here is what it does now.
First start of the morning: Works fine. Initializes properly and settles on “0”. In operation it reports boost numbers consistent with the scanmaster (v 2.2 reports boost and vacuum)
Subsequent starts: Gauge immediately goes to “Sender error” and stays that way. No function at all.
All starts: If you just turn the key on but don’t start the car it initializes normally and settles on “0”. If this is a “subsequent” start as soon as I start the car it shifts to “Sender error”
I have replaced the sender and sender harness. Speedhut has replaced the circuit board twice. None of these have changed anything.
I have tried resetting everything after that initial start by disconnecting the battery for an hour. No change,
I have tried disconnecting the gauge after it has gone to sender error and then reconnecting it. It just goes right back to sender error.
Speedhut has advised me that the gauge ignores vacuum/boost conditions when initializing. They say all it looks at is the 5 volt signal.
Maddeningly it works the first start of the day all the time.
What am I missing?