Electrical Wizard Needed- Limited Power
08-01-05, 11:17 PM
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Electrical Wizard Needed- Limited Power
Help!
I have a 1990 RX7 Convertable that has developed an electrical problem similiar to what others have described...Interior and headlights, horn and the door locks work. No power to anything else (idiot lights, starter, power windows, radio, etc). This started as an intermittant problem, I would stop, come back to the car and have no power. After a few minutes the power would come back. To me it acted like a bad relay. I stoped driving the RX7 for a few days, only test started it without problems, so I took it for a drive and had to tow it home. Since the tow home I have only gotten one momentary burst of energy. The car only has 65,000 miles, is in fairly good shape, but I know nothing if its history except that I had to have the engine rebuilt after I bought it last year.
I have searched and checked out what has been suggested to others, but most threads end without a resolution.
The ignition switch checks out for continuity. The black battery wire has 8 volts at the ignition switch connector, but I only have about 1 volt at the solder connection on the ignition switch. I checked out the main relay and it works, but I only have miliamps at the 12V activation connector for the main relay. I have 12 volts at the battery and at the interior lights, so I do not understand what is dropping the voltage.
When I had the intermittant problem I called the mechanic who rebuilt the engine, but he did not seem to have any idea why it was happening, so I am reluctant to take it to him for an open ended diagnostic bill. Any ideas would be appreciated!
Steve
I have a 1990 RX7 Convertable that has developed an electrical problem similiar to what others have described...Interior and headlights, horn and the door locks work. No power to anything else (idiot lights, starter, power windows, radio, etc). This started as an intermittant problem, I would stop, come back to the car and have no power. After a few minutes the power would come back. To me it acted like a bad relay. I stoped driving the RX7 for a few days, only test started it without problems, so I took it for a drive and had to tow it home. Since the tow home I have only gotten one momentary burst of energy. The car only has 65,000 miles, is in fairly good shape, but I know nothing if its history except that I had to have the engine rebuilt after I bought it last year.
I have searched and checked out what has been suggested to others, but most threads end without a resolution.
The ignition switch checks out for continuity. The black battery wire has 8 volts at the ignition switch connector, but I only have about 1 volt at the solder connection on the ignition switch. I checked out the main relay and it works, but I only have miliamps at the 12V activation connector for the main relay. I have 12 volts at the battery and at the interior lights, so I do not understand what is dropping the voltage.
When I had the intermittant problem I called the mechanic who rebuilt the engine, but he did not seem to have any idea why it was happening, so I am reluctant to take it to him for an open ended diagnostic bill. Any ideas would be appreciated!
Steve
08-02-05, 09:05 AM
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Whoa. Someone who has actually checked the black wire at the ignition switch leads. Eeek!
I'd suspect that wire because it has only 8vdc when the battery is 12vdc. Follow it back from the igniton switch back to the connector about six to ten inches below the engine fuse box.
Actually that black wire also is spliced into the alternators output wire. Possible cause there also??
I'd suspect that wire because it has only 8vdc when the battery is 12vdc. Follow it back from the igniton switch back to the connector about six to ten inches below the engine fuse box.
Actually that black wire also is spliced into the alternators output wire. Possible cause there also??
08-02-05, 10:20 AM
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if you loose power, then you disconnect the battery (for about 10 seconds at least), and then reconnect, does power come back to normal?
give that a try, and if so then it sounds like a ground issue.
give that a try, and if so then it sounds like a ground issue.
08-03-05, 01:56 AM
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Thanks for the suggestions! I disconnected the battery (again) and this did not make any difference. While I had the battery disconnected I used cables to jump from my Durango since my piston mechanic suggested that the battery could have a bad cell. Still nothing. I have power at the alternator and the splice "looks" good.
I probably will not have time to play with it till Sunday. I may buy a new battery and see if an installed battery might make a difference. I may also make a long jump wire to go from the battery to the ignition switch to see if that makes a difference.
Any other suggestions?
I probably will not have time to play with it till Sunday. I may buy a new battery and see if an installed battery might make a difference. I may also make a long jump wire to go from the battery to the ignition switch to see if that makes a difference.
Any other suggestions?
08-03-05, 07:28 AM
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when you loose power, are you still able to push-start the car, or do you need to get the power back first?
also, before going to buy a new battery, a lot of places will test your battery for free and let you know if you need a new one. i get mine tested at a local battery store.
- Aaron
also, before going to buy a new battery, a lot of places will test your battery for free and let you know if you need a new one. i get mine tested at a local battery store.
- Aaron
08-03-05, 08:48 AM
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Ok. Your voltmeter and fuel gauge do not work along with the idiot lights. BUT the headlights and interior lights work plus horn etc.
That is a common problem when you don't get power from the BLACK wire that leads from the 80amp Main Fuse in the engine fuse box to the BLACK wire on the three igniton switch plugs.
If you pull apart the two wire connector at the ignition switch and read the voltage at the BLACK wire it should read battery voltage what ever that happen to be at the moment.
IF it does not, then you have a bad wire/connection on that BLACK wire or its connection to the engine fuse box.
NORMALY if you disconnect that ignition switch plug that has a BLACK wire and a BLACK AND WHITE wire in it, then put a jumper wire b/t the BLACK and the BW wire, the fuel gauge should now rise and the voltmeter on the combination meter should now rise to battery voltage plus if you now turn the turn signals to left or right they should now work.
If that happens only when you jumper the BLACK and the BW wire, but NOT when the plug is connected up normally and the key is to ON...........then I say you have a bad ignition switch.
But you said that the battery voltage was 12 and you only read 8 at the BLACK wire so I'd suspect a bad BLACK wire b/t the engine fuse box and the ignition switch OR the alternator is dragging the voltage down thru a internal short (not likely).
I assume when you turned the headlights on they were bright and the retractors went up/down as you turned the lights on/off. Meaning the battery is good enough to supply enough voltage to the combination meter/turn signals/idiot lights. Things you are not getting power to.
That is a common problem when you don't get power from the BLACK wire that leads from the 80amp Main Fuse in the engine fuse box to the BLACK wire on the three igniton switch plugs.
If you pull apart the two wire connector at the ignition switch and read the voltage at the BLACK wire it should read battery voltage what ever that happen to be at the moment.
IF it does not, then you have a bad wire/connection on that BLACK wire or its connection to the engine fuse box.
NORMALY if you disconnect that ignition switch plug that has a BLACK wire and a BLACK AND WHITE wire in it, then put a jumper wire b/t the BLACK and the BW wire, the fuel gauge should now rise and the voltmeter on the combination meter should now rise to battery voltage plus if you now turn the turn signals to left or right they should now work.
If that happens only when you jumper the BLACK and the BW wire, but NOT when the plug is connected up normally and the key is to ON...........then I say you have a bad ignition switch.
But you said that the battery voltage was 12 and you only read 8 at the BLACK wire so I'd suspect a bad BLACK wire b/t the engine fuse box and the ignition switch OR the alternator is dragging the voltage down thru a internal short (not likely).
I assume when you turned the headlights on they were bright and the retractors went up/down as you turned the lights on/off. Meaning the battery is good enough to supply enough voltage to the combination meter/turn signals/idiot lights. Things you are not getting power to.
08-03-05, 10:32 AM
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DISCLAIMER: I only have a series four wiring diagram. You have a series five. I'm doing a lot of assumptions about wire colors. I assume they left the wire colors the same at the ignition switch. If you don't see one of the three ignition switch connectors with just two wires, one BW and the other pure B, then forget what I said. I'm talking about the two wire connector on the harness side of the ignition switch, NOT the switch side of the connector. Colors change on the ignition switch pigtail.
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08-04-05, 12:48 AM
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Hailers,
I have looked at the on line series 5 info so I think I am adapting where needed, but your suggestions have made sense. The solid black wire seems to change to black with a white stripe at some places (such as at the alternator). I am hoping to take the battery in on Friday and have it checked to eliminate that as an issue before I do any more troubleshooting. The headlights were bright before and after I got the 8 volt readings, but batteries can do strange things.
Last night I did disconnect the battery and jump from my durango to the RX7 battery connectors, this did not make any difference. Your thought about the alternator being bad is a thought I also had.
I was reading about the ECU and there was a reference about it controlling the idiot lights and a lot of other things. Have you had any experience with the ECU going bad?
I am hoping to have time Sunday to experiment with a jump wire. Aftet that it will probably go to my friend who is great piston mechanic. He has figured out a couple of weird things on other cars for me!
Steve
I have looked at the on line series 5 info so I think I am adapting where needed, but your suggestions have made sense. The solid black wire seems to change to black with a white stripe at some places (such as at the alternator). I am hoping to take the battery in on Friday and have it checked to eliminate that as an issue before I do any more troubleshooting. The headlights were bright before and after I got the 8 volt readings, but batteries can do strange things.
Last night I did disconnect the battery and jump from my durango to the RX7 battery connectors, this did not make any difference. Your thought about the alternator being bad is a thought I also had.
I was reading about the ECU and there was a reference about it controlling the idiot lights and a lot of other things. Have you had any experience with the ECU going bad?
I am hoping to have time Sunday to experiment with a jump wire. Aftet that it will probably go to my friend who is great piston mechanic. He has figured out a couple of weird things on other cars for me!
Steve
08-04-05, 01:03 AM
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Before you go worrying about the ECU I would get battery voltage to the ignition switch. I try and work the higher priority problems first. Without good power you're going nowhere. At least until the tow truck shows up. 
Since this all starts with the battery get it checked and charged and go from there. Make sure the 80 amp fuse is bolted in tightly. And listen to Hailers! 
Since this all starts with the battery get it checked and charged and go from there. Make sure the 80 amp fuse is bolted in tightly. And listen to Hailers!
08-04-05, 11:25 AM
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I agree. Your getting off track. That black wire, on a series four, feeds the ignition switch. When you turn the key to On or better it feeds the Black/White wire I mentioned earlier. That black/white wire feeds an electrical bus of fuses in the interior fuse box.
THAT Black/White wire is NOT the same as the one you see on the alternators small plug
The ignition switch harness plugs are about a foot from the switch itself. You have to remove a air conditioning duct that's held on with two phillips screws to see the THREE ignition switch plugs. One of the plugs has TWO wires in it. One is pure black coming from the engine bay. The other is Black/White and feeds part of the fuse box in the interior.
If you disconnect the plug with the Black wire and the Black/White wire........then jumper the two with a piece of wire, you will see that the idiot lights light up, the turn signals work and the fuel and battery gauges move.
I think that the BLACK wire you mentioned in one of your first post is NOT the one I'm talking about. So.....pull the plug off the ignition switch that has a Black and a Black/White wire. See if you have battery voltage on the Black wire. It should read the same as the battery. If it does NOT, then you have a problem with that one wire. It goes back to the engine fuse box thru a connector about six to ten inches below the engine fuse box.
If you have 12v on that Black wire I mentioned just above, and you can jumper that Black wire to the Black/White wire in that connector and get the gauge/idiot lights/turn signals to work that way, then you have a bad ignition switch.
The ECU has nadda to do with the idiot lights/gauges etc.
Many things work on this car without any power going to the ignition switch. Such as the headlights. They work off a different bus on the interior fuse box than say the turn signals/idiot lights/gauges.
That is why I am sure you have a ignition switch power problem and not something else. Ignition key functions don't work but you have headlights. Two seperate circuits and the battery must be good or else the headlight wouldn't rise/fall when the lights were turned on/off.
Concentrate on the BLACK wire in the two socket ignition switch about a foot below the switch itself.
THAT Black/White wire is NOT the same as the one you see on the alternators small plug
The ignition switch harness plugs are about a foot from the switch itself. You have to remove a air conditioning duct that's held on with two phillips screws to see the THREE ignition switch plugs. One of the plugs has TWO wires in it. One is pure black coming from the engine bay. The other is Black/White and feeds part of the fuse box in the interior.
If you disconnect the plug with the Black wire and the Black/White wire........then jumper the two with a piece of wire, you will see that the idiot lights light up, the turn signals work and the fuel and battery gauges move.
I think that the BLACK wire you mentioned in one of your first post is NOT the one I'm talking about. So.....pull the plug off the ignition switch that has a Black and a Black/White wire. See if you have battery voltage on the Black wire. It should read the same as the battery. If it does NOT, then you have a problem with that one wire. It goes back to the engine fuse box thru a connector about six to ten inches below the engine fuse box.
If you have 12v on that Black wire I mentioned just above, and you can jumper that Black wire to the Black/White wire in that connector and get the gauge/idiot lights/turn signals to work that way, then you have a bad ignition switch.
The ECU has nadda to do with the idiot lights/gauges etc.
Many things work on this car without any power going to the ignition switch. Such as the headlights. They work off a different bus on the interior fuse box than say the turn signals/idiot lights/gauges.
That is why I am sure you have a ignition switch power problem and not something else. Ignition key functions don't work but you have headlights. Two seperate circuits and the battery must be good or else the headlight wouldn't rise/fall when the lights were turned on/off.
Concentrate on the BLACK wire in the two socket ignition switch about a foot below the switch itself.
Last edited by HAILERS; 08-04-05 at 11:28 AM.
08-16-05, 03:51 PM
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The RX7 is running!
The connector just below the fuse block was bad. It looked OK, but I could not get it apart. Spliced in a new one and everything is fine. I appreciate your suggestions and keeping me focused on the Black wire!
Steve
The connector just below the fuse block was bad. It looked OK, but I could not get it apart. Spliced in a new one and everything is fine. I appreciate your suggestions and keeping me focused on the Black wire!
Steve
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