1989 porsche 928 will not start

No. I mean at the actual plug connections seen at the lowest point of the CE board. Sorry, my choice of the word "terminal" was a very poor one as point "8" of the connection is not "terminal 8." But, nevertheless, be sure that your performing this test at point "x" of the plug connections. Disconnecting your battery is not necessary.

If your still a little unsure of what I mean, this test is not that significant because it won't tell us anything specifically about that circuit. Though, if the results were a higher value, it would prove a break. To be frank with you, I would be willing to bet that your ecu has failed. That being said, you need to get in contact with Rich from electronikrepair.com/

austin the ecu is good i go it replaced by jds porsche, it didnt even needed to be replaced

I took it to the mechanic this week i will post an update on the cause of the problem once it gets fixed and i get another extremly high bill

OUCH!! that sucks

The LH fuel injection module provides the switch to ground for the fuel injectors, it does not provide the "power" to the system.

The fuel injector system voltage is provided by the LH Relay, which is "turned on" by the LH when the ignition is turned on.

So, the proper diagnostics is to jumper the LH relay and check to see if there is battery voltage at the fuel injectors, and at the LH connector pin positions that correspond with 12V system power.

Note, on 1984 Euro, 1985 - 1986 Porsche 928 LH systems, the fuel injector voltage is provided by the fuel pump relay.

I can provide a detailed theory of spark and fuel injection operation white paper in PDF format, just drop a line to my This email address is being protected from spambots. You need JavaScript enabled to view it. email address.

For what it's worth, I picked up my 1985 928S for next to nothing because the dealer kept looking for issues with wiring, computers, starters, etc on a no start situation.

After spending a couple hours with the multimeter, I found 4 bad relays. (LH Computer, EZF Computer, don't remember what else). Replaced them and it fired right up. I talked the seller down almost $1000 for what turned out to be $10 in parts.