Hello. I realize it is difficult to diagnose electrical issues over the Internet, but thought I would try the forums to see if I am missing anything real obvious (or not so obvious). I’ll give a background on the car and then describe what I am seeing with the electrical system. This is a long post, but I don’t know how to ask for any kind of help without defining the problem and surrounding factors as best as possible.
My car is a 1987 T-Type. Over the last year or so a lot of work has been done on the car, including a motor re-build (still stock 109 block), back-half suspension, TH400, battery relocate (with all of the associated wiring), etc… Over the past 4-6 months everything was re-installed after the suspension work and I slowly began the process of getting the car back into race form.
The battery is an Optima yellow-top (2nd one), with all main wiring to ground and 12V power 0/1 gauge run through a battery shut-off switch. All of the main grounds outside of the motor are joined with a stud welded to the frame. This location serves as the main ground for the body, the transmission, the battery 0/1 wire, etc… Similarly, a positive junction box was used to serve as the main power supply for the starter and alternator. All wiring to and from the +/- junction boxes is brand new, solder connected, and verified as connected properly. Additional grounds for the motor are located in the stock location on the firewall using Casper’s ground junction box. Again, all apparent motor grounds have been checked and connections verified. Since the dash was out of the vehicle to install the front crash bar, I was concerned about connections here (more to come on that). Several grounds on each side of the dash did not appear to be well connected – these were repaired. In addition, all accessory grounding (lights, tachometer, etc.) were checked and verified through proper function of each unit.
After working through several mechanical issues with the roller rockers, I began to notice that the vehicle was not charging properly. The vehicle would only make 11-12 volts under power – basically whatever the battery would put out. After noticing the low voltage under power (through Direct Scan) I used my Scanmaster and noticed that the voltage was low all of the time. Not knowing what the problem was, I began to problem solve (with the help of Banning and several other Magna members). Initial diagnosis revealed that the vehicle was sending 12V to ground at some point, causing voltage to run through the car where it shouldn’t. For example, using a multi-meter attached to the battery and then touched to the fuel cell ring would reveal anywhere from 5-17 mv of electrical current. Troubling to say the least… It appears that this condition was solved after correcting the aforementioned cockpit grounds and also correcting an under-hood wiring condition that was incorrect. After these repairs, the voltage was no longer seen on a grounded portion of the car. Next was an alternator swap, with Banning’s car used as the test mule. After installing his alternator I immediately had a charging vehicle with voltage in the high 13’s / low 14s – just as it should be. Thinking that the alternator was the final culprit, I acquired a new one (AC Delco re-man through local Chevy Pro Shop) and installed that on the car. After firing up the car, I again had high 13s / low 14s at idle. Everything appeared to be fine. Off to Cecil County…
On my second pass down the track (first was a wash, no boost due to controller being backed all the way off) I completed a solid burnout and lined up. Used the foot brake to leave at around 3000 RPM and took off. The car seemed to be driving normally, and then almost completely shut off at 5800 RPM right before the 1-2 shift. It picked back up and then repeated this condition between the 2-3 shift. I coasted through the lights and ended up with a 14-something at 70+ MPH. Not what I expected. After returning the car to the trailer the Direct Scan files were pulled up and it was apparent that my voltage issues still existed. I would only get 11.2 volts or so going down the track, and at one point (right around the 1-2 shift) it actually dropped below 10 volts. I started the car and looked at the Scanmaster voltage at idle – 11-ish volts. Needless to say the car cannot be run in this condition. Back to the shop…
First step was to swap alternators again. Doing this, with a known good alternator, I instantly had a charging system again with the expected high 13s / low 14s. My alternator was installed on a known good car and the system would not charge on that car either – showing voltage in the mid-11s. So at this point I am down to two basic questions: 1) Did I get a bad alternator (2nd one)?, or 2) Do I have something else wrong that is not only eliminating my charging condition but also frying the alternator (and if so, what)?
One other thing to add is the little demon know as the battery voltage idiot light on the dash. This light would not come on, although I had not even been looking for it through all of the previous time working on the car. The instrument cluster has been verified as in working condition, but the connection between the cluster and the cockpit is poor. The cockpit does not fit like stock since it was out of the car with the crash bar installed behind it. I will be working on a method to ensure that this connector is properly seated and the printed circuit connection is secure. However… I am using Casper’s battery on/off switch set-up and it says (I think – help me out John if I am messed up) to interrupt the brown wire at the alternator. Right now my brown wire is not hooked up at all – I have a volt booster plugged in at the top of the alternator and the alternator receives 12V straight from the battery switch as connected through the volt booster. Several problem solving attempts disconnecting the volt booster and trying to re-attach the brown wire have not fixed the problem, although the voltage idiot light was also probably not working at that time.
Sorry for dragging on… Please offer any assistance you have. All thoughts are welcome. Ask questions if you do not understand something I wrote above.
Michael
My car is a 1987 T-Type. Over the last year or so a lot of work has been done on the car, including a motor re-build (still stock 109 block), back-half suspension, TH400, battery relocate (with all of the associated wiring), etc… Over the past 4-6 months everything was re-installed after the suspension work and I slowly began the process of getting the car back into race form.
The battery is an Optima yellow-top (2nd one), with all main wiring to ground and 12V power 0/1 gauge run through a battery shut-off switch. All of the main grounds outside of the motor are joined with a stud welded to the frame. This location serves as the main ground for the body, the transmission, the battery 0/1 wire, etc… Similarly, a positive junction box was used to serve as the main power supply for the starter and alternator. All wiring to and from the +/- junction boxes is brand new, solder connected, and verified as connected properly. Additional grounds for the motor are located in the stock location on the firewall using Casper’s ground junction box. Again, all apparent motor grounds have been checked and connections verified. Since the dash was out of the vehicle to install the front crash bar, I was concerned about connections here (more to come on that). Several grounds on each side of the dash did not appear to be well connected – these were repaired. In addition, all accessory grounding (lights, tachometer, etc.) were checked and verified through proper function of each unit.
After working through several mechanical issues with the roller rockers, I began to notice that the vehicle was not charging properly. The vehicle would only make 11-12 volts under power – basically whatever the battery would put out. After noticing the low voltage under power (through Direct Scan) I used my Scanmaster and noticed that the voltage was low all of the time. Not knowing what the problem was, I began to problem solve (with the help of Banning and several other Magna members). Initial diagnosis revealed that the vehicle was sending 12V to ground at some point, causing voltage to run through the car where it shouldn’t. For example, using a multi-meter attached to the battery and then touched to the fuel cell ring would reveal anywhere from 5-17 mv of electrical current. Troubling to say the least… It appears that this condition was solved after correcting the aforementioned cockpit grounds and also correcting an under-hood wiring condition that was incorrect. After these repairs, the voltage was no longer seen on a grounded portion of the car. Next was an alternator swap, with Banning’s car used as the test mule. After installing his alternator I immediately had a charging vehicle with voltage in the high 13’s / low 14s – just as it should be. Thinking that the alternator was the final culprit, I acquired a new one (AC Delco re-man through local Chevy Pro Shop) and installed that on the car. After firing up the car, I again had high 13s / low 14s at idle. Everything appeared to be fine. Off to Cecil County…
On my second pass down the track (first was a wash, no boost due to controller being backed all the way off) I completed a solid burnout and lined up. Used the foot brake to leave at around 3000 RPM and took off. The car seemed to be driving normally, and then almost completely shut off at 5800 RPM right before the 1-2 shift. It picked back up and then repeated this condition between the 2-3 shift. I coasted through the lights and ended up with a 14-something at 70+ MPH. Not what I expected. After returning the car to the trailer the Direct Scan files were pulled up and it was apparent that my voltage issues still existed. I would only get 11.2 volts or so going down the track, and at one point (right around the 1-2 shift) it actually dropped below 10 volts. I started the car and looked at the Scanmaster voltage at idle – 11-ish volts. Needless to say the car cannot be run in this condition. Back to the shop…
First step was to swap alternators again. Doing this, with a known good alternator, I instantly had a charging system again with the expected high 13s / low 14s. My alternator was installed on a known good car and the system would not charge on that car either – showing voltage in the mid-11s. So at this point I am down to two basic questions: 1) Did I get a bad alternator (2nd one)?, or 2) Do I have something else wrong that is not only eliminating my charging condition but also frying the alternator (and if so, what)?
One other thing to add is the little demon know as the battery voltage idiot light on the dash. This light would not come on, although I had not even been looking for it through all of the previous time working on the car. The instrument cluster has been verified as in working condition, but the connection between the cluster and the cockpit is poor. The cockpit does not fit like stock since it was out of the car with the crash bar installed behind it. I will be working on a method to ensure that this connector is properly seated and the printed circuit connection is secure. However… I am using Casper’s battery on/off switch set-up and it says (I think – help me out John if I am messed up) to interrupt the brown wire at the alternator. Right now my brown wire is not hooked up at all – I have a volt booster plugged in at the top of the alternator and the alternator receives 12V straight from the battery switch as connected through the volt booster. Several problem solving attempts disconnecting the volt booster and trying to re-attach the brown wire have not fixed the problem, although the voltage idiot light was also probably not working at that time.
Sorry for dragging on… Please offer any assistance you have. All thoughts are welcome. Ask questions if you do not understand something I wrote above.
Michael
