Car dying, what's going on?

[ricko1966]

Push comes to shove I'd adapt on a gm 1 wire alternator. It is 1 wire to the battery, that is it.I convert the late 70's early 80's gm 3 wires to 1 wire operation for my oddball projects. I do that because the 3 wires are dirt cheap and super common example would be 1978 monte carlo 305 v8 alternator.You don't even need a car Just for s##ts and giggles I made a backup generator with 1 I spin it with a 5hp honda engine charge 3 deep cycle batteries wired in parallel 1500 watt inverter and the beauty is it doesn't have to run constantly just little 30 minute runs every now and then to bring the batts back up.

[1990new]

Revised and added more info in subsequent post. Festiva GTX replied in between. Yes that's what I understood. The idiot light triggers the alternator to produce, so I assume it was there in the original orange tach. The car has been running fine for several so it looks like the Tach swap has nothing to do with it.

[Festiva GTX]

I am restarting this 5 year old thread because I started having the same problem with Trixie. I thought it was the alternator and had planned to put a larger amp alternator on here because of the power windows. I started looking at the conversion option and am now getting more confused.
Trixie is a 1989 automatic with EFI. The alternator wires connections are both on the side. She originally had an orange non-tach cluster but I switched that out to a white tach cluster several years ago. I noticed that the cluster has a 100ohms resistor in the instrument cluster where the batter light goes in the back of the cluster. I sold the old red cluster so I don't know if it had the resistor built in to it. Anyone know it it has the 100ohms resistor, which I assume triggers the alternator to generate current?

As what I can remember, all most stock alternator will work fine if have one idiot bulb circuit working. if idiot bulb removed or burned out it may cause to alternator stop generating 12v.

[1990new]

I am restarting this 5 year old thread because I started having the same problem with Trixie. I thought it was the alternator and had planned to put a larger amp alternator on her because of the power windows. I started looking at the conversion option and am now getting more confused.
Trixie is a 1989 automatic with EFI. The alternator wires connections are both on the side. She originally had an orange non-tach cluster but I switched that out to a white tach cluster several years ago. I noticed that the cluster has a 100ohms resistor in the instrument cluster where the battery light goes in the back of the cluster. I sold the old red cluster so I don't know if it had the resistor built in to it. Anyone know it it has the 100ohms resistor, which I assume triggers the alternator to generate current? I tested for ohms across the contacts for the light and it read 104 ohms so it is good. I bench tested the alternator using an instrument bulb between the connector for the cluster charge light and ground. When I spin up the alternator using a drill the charge get up to 12 to 15 amps and the bulb light goes out a clamp amp meter on the positive cable to the battery initially show about 6 Amp and starts going down as I spin the alternator.
So it appears that the alternator is working fine on the bench.
Any suggestions?

Thanks... Festiva GTX that idiot light appears to be working as it should so on with my search.

[Festiva GTX]

If your alternator okay on bench test and have you checked the fuses? The front 3 main wire link fuse sometime can't seen inside burn out fuse but your meter tester can verify if its bad or good.

[1990new]

If your alternator okay on bench test and have you checked the fuses? The front 3 main wire link fuse sometime can't seen inside burn out fuse but your meter tester can verify it.

Thanks.. will continue the checking tomorrow after I reinstall the alternator and verify that the charge from it is getting to the battery.

[1990new]

If your alternator okay on bench test and have you checked the fuses? The front 3 main wire link fuse sometime can't seen inside burn out fuse but your meter tester can verify it.

Thanks.. will continue the checking tomorrow after I reinstall the instrument panel and alternator and verify that the charge from it is getting to the battery.

[Festiva GTX]

Thanks.. will continue the checking tomorrow after I reinstall the instrument panel and alternator and verify that the charge from it is getting to the battery.

Your welcome and I think you can upgrade to FLF Series Cartridge Fuses it allowed you to see the little window to see the status fuse intact.

[1990new]

Your welcome and I think you can upgrade to FLF Series Cartridge Fuses it allowed you to see the little window to see the status fuse intact.

Have had cartridge fuses for a long time.. I keep fusible links spares in the glove compartments though just in case there is is temporary initially spike that could blow the fuse but would not the burn the fusible link before is dissipates.

[bravekozak]

It was the ECU itself. The main power capacitor had gone bad in it. The ECU would stop sending signal to the main relay and the fuel and ignition would be cut. This only happened when the car was warm.

[1990new]

It was the ECU itself. The main power capacitor had gone bad in it. The ECU would stop sending signal to the main relay and the fuel and ignition would be cut. This only happened when the car was warm.

That's why it was so hard to diagnose. ECU failures are rare in my experience and one of the last things that people think about. Wonder if that happened before or after the friend connected the jumper cables backward.

How do you test for that?

[Festiva GTX]

It was the ECU itself. The main power capacitor had gone bad in it. The ECU would stop sending signal to the main relay and the fuel and ignition would be cut. This only happened when the car was warm.

Wow, that must be rare.
So far I did owned various of 22+ Ford Festiva in the past and nope them have faulty ECU but my 1989 Chevy C3500 and 1987 Mazda B2600i truck did had ECU faulty. It would ran perfect when its cold and about in 10 min later it become like sick engine miss firing, lost power and dies out on me. when ECU is cool down and it would reset the clock and run good but same problem appear after 10 min of driving or sit idling.

[Festiva GTX]

That's why it was so hard to diagnose. ECU failures are rare in my experience and one of the last things that people think about. Wonder if that happened before or after the friend connected the jumper cables backward.

How do you test for that?

Only way to see if your ECU is still good... Pull your ECU out and open the lid Inspect it all the capacitors or any burn marks. If any capacitor(s) at top popped out then you need to swap same match of new capacitor(s)

[WmWatt]

re post #40 - ignition control module (ICM) is another electroinc device which exhibits same behaviour - ie warms up and dies stalling engine - engine will restart when cool until it no longer does at which time ICM is dead, stone dead

[1990new]

Turns out there was corrosion on the terminal connector that sensed battery voltage. Got all the terminals cleaned up.
My original 89 (old style) alternator is back on Trixie and is charging fine.

I used my adapter plug to bench test the two newer style alternators again and they work fine too. They spin up and put out 14.3 volts as the light goes out and then the load on the drill gets lighter and the voltage goes up to 17 as the amps draw to recharge the battery go down. Same thing happened on both alternators.

I am attaching a picture of the connector I made to adapt the old alternator terminals to the newer style alternator.

From the manual diagrams the red sensor (S) (90-93) wire goes directly back to the battery thru the head fusible link, but on the 89 (I) red wire (Bk/W in the old style terminal) goes back thru the ignition and is connected to the battery when the ignition on position.

In addition to the adapter wire you have to widen the charge (White) wire going to the B terminal on the alternator because the post larger on the 90 and later alternator. I you were going to adapter the larger amp alternator it probably would be a good idea to replace this white wire going back to the battery for charging with a larger gauge wire to carry the higher amps when it is called for.

In the picture the S (Red Wire) is the I wire (Bk/W) on the old style alternator terminal and the L wire in adapter will connect to the BK/R wire going to the charge lamp on the cluster.

Hope I made this clear.. If anyone has corrections wants to add further clarification, please feel free to add on.
Alternator plug adapter.jpg