87 944 Turbo - electrical trouble

[Raulg]

The car has had an issue with low voltage displaying on the dashboard for a while.
Upon start-up the needle indicates below 12 volts. If the engine is rev for a few seconds past 2000 rpm, the needle will go past 12 volts and will operate apparently normal until the next start-up.

I cleaned as many grounds as I could find and could not solved this condition. I figure I would have to live with it.

Lately, when I use the turn signal or turn the headlights on, the radio will turn off for a couple of seconds and come back on. It is happening more frequently now.

Where should I look? Is there a relay that powers the dashboard, headlights and radio?
Thank you in advance for any advice.
Raulg

[944 Ecology]

1) Start your car.

2) Turn on your headlights and radio.

3) One by one, pull the relays. When your headlights go out, that relay controls the headlights.

4) When your radio goes off, that relay controls your radio.

5) You're welcome.

[Raulg]

George,
Thank you for the advice. I will try that tonight.
I will report back.
Raul

[Raulg]

George,
I tried pulling all the relays, one by one.
None caused the radio or the headlights to go off. The DME turned the engine off when pulled, as expected.
Where else can I look?
Thank you
Raul

[944 Ecology]

The X relay is in position G14, and should be controlling both the radio and the headlights.

Try again, this time with the engine running and the headlights on.

If that doesn't work, you may have a cob job done by a PO, and there is no fix for that other than using a wiring diagram to figure out what has been done.

[mytrplseven]

Clue: blue wire to the Alternator Field, if not connected, will cause the alternator to remain dis-energized until engine is running at or above 2000 rpm, when the alternator becomes self-energized and then functions normally.

[Raulg]

George:
I tried again this afternoon, taken the X relay out while the engine was running, headlights on and radio on. No changes. The radio didn't stop, the engine didn't stall.
The relay in my car looks very shallow unlike the ones shown on the PP website.Thank you for your advise.

mytrplseven,
Thank you for trying to help. How would I get to the blue wire?
I replaced the alternator a while back and don't remember seeing a blue wire.
I hope you can provide me with a little more information.

Thank you both
raulg

[Raulg]

mytrplseven,
I looked at some photos of when I replaced the alternator. I can see a thin blue wire attached to the back/top of the alternator. The other wire appears to be brown and thicker.
Is this the blue wire you refer to?
If the wire is connected, could it be broken internally? If so, could I install a replacement wire? where does it connect at the other end?
Thank you for any advice you can provide.

After the car revs to 2000, the voltage reads normal, it goes back to idle and it indicates above 12 volts. Could this happen with a bad blue wire?
Thank you
Raulg

[Raulg]

Are 944s and turbos supposed to have a chassis ground cable between the engine and body, similar to a 911?
I f so, where should it be located?
Thank you
Rg

[soxnail]

Have you used a Volt meter to look at the actual voltage ?
Gauges on the car may not be correct.
Sox

[mytrplseven]

Originally Posted by Raulg

Are 944s and turbos supposed to have a chassis ground cable between the engine and body, similar to a 911?
I f so, where should it be located?
Thank you
Rg

On some year cars, the blue wire comes from the alarm. Don't know if your car year is one. See if you can find a wiring diagram for the 87 car. There should be a ground strap between the engine block and the firewall. Location is typically from rear of the passenger side cam tower area to the firewall.

[Raulg]

I started looking for a replacement alternator wire harness thinking one of the wires may be damaged within the insulator. In looking at pictures of the harness, I noticed this white connector.
I looked for it in the car and found it buried under other wiring near the top of the brake booster.

I unplugged it to check the connection. It looked clean. I plugged it back in and now the alternator gauge works fine as soon as I start the car. It has been good for a week or so. I hope that is it for the voltage display.

The radio keeps cutting out when I turn the headlights on and/or the turn signals. I noticed that sometimes it loses power even if the headlights/turn signals are off. So the mystery continues.

I will replace the X-relay next. It is inexpensive enough.
I still haven't found a ground strap from the engine to the body. There is a ground wire from the back of the engine to the battery.

Any advice would be appreciated.
Thank you
Raul

[Raulg]

I replaced the X relay and the only difference I noticed is that the radio doesn't turn off for a couple of minutes, until the car warms up. Then is the same as before.
Does anyone have any ideas?
RG