Engine Runs If "GAUGES TRANS" Fuse is Installed
#1
Engine Runs If "GAUGES TRANS" Fuse is Installed
Background:
The car is a 68 w/ HEI powered by a relay triggered by the original coil feed wire. It also has aftermarket rally pack gauges installed, that function when the fuse is installed.
Symptom 1:
If the fuse in the "GAUGES TRANS" (lower right of fuse block) is installed, the engine keeps running when the key is turned off. It turns off fine when the fuse is removed.
Symptom 2:
With the car off, key in "run", and "GAUGES TRANS" fuse removed, the gauges have power. Not enough to function, they just move off of zero to a static spot.
Between 1 and 2 above, it looks like there is "stray" voltage on both sides of the fuse in that circuit. Voltage readings confirm this (with fuse removed). Does this mean I have a bad fuse block, or is there an alternate explanation?
I spent about 4 hours out in the heat trying to figure this out, would be appreciative of any pointers. I've attached my readings/notes.
Thanks.
The car is a 68 w/ HEI powered by a relay triggered by the original coil feed wire. It also has aftermarket rally pack gauges installed, that function when the fuse is installed.
Symptom 1:
If the fuse in the "GAUGES TRANS" (lower right of fuse block) is installed, the engine keeps running when the key is turned off. It turns off fine when the fuse is removed.
Symptom 2:
With the car off, key in "run", and "GAUGES TRANS" fuse removed, the gauges have power. Not enough to function, they just move off of zero to a static spot.
Between 1 and 2 above, it looks like there is "stray" voltage on both sides of the fuse in that circuit. Voltage readings confirm this (with fuse removed). Does this mean I have a bad fuse block, or is there an alternate explanation?
I spent about 4 hours out in the heat trying to figure this out, would be appreciative of any pointers. I've attached my readings/notes.
Thanks.
#2
Background:
The car is a 68 w/ HEI powered by a relay triggered by the original coil feed wire. It also has aftermarket rally pack gauges installed, that function when the fuse is installed.
Symptom 1:
If the fuse in the "GAUGES TRANS" (lower right of fuse block) is installed, the engine keeps running when the key is turned off. It turns off fine when the fuse is removed.
Somehow you are back feeding voltage to the relay causing it to stay engaged or its wired wrong.
Symptom 2:
With the car off, key in "run", and "GAUGES TRANS" fuse removed, the gauges have power. Not enough to function, they just move off of zero to a static spot.
I don't know which aftermarket gauge set you have, the voltmeter or amp gauge, or idiot light has power on the other side when the key is on. Voltage will back feed through that circuit. Is there anything connected to the IGN terminal in the fuse block?
Between 1 and 2 above, it looks like there is "stray" voltage on both sides of the fuse in that circuit. Voltage readings confirm this (with fuse removed). Does this mean I have a bad fuse block, or is there an alternate explanation?
I spent about 4 hours out in the heat trying to figure this out, would be appreciative of any pointers. I've attached my readings/notes.
Thanks.
The car is a 68 w/ HEI powered by a relay triggered by the original coil feed wire. It also has aftermarket rally pack gauges installed, that function when the fuse is installed.
Symptom 1:
If the fuse in the "GAUGES TRANS" (lower right of fuse block) is installed, the engine keeps running when the key is turned off. It turns off fine when the fuse is removed.
Somehow you are back feeding voltage to the relay causing it to stay engaged or its wired wrong.
Symptom 2:
With the car off, key in "run", and "GAUGES TRANS" fuse removed, the gauges have power. Not enough to function, they just move off of zero to a static spot.
I don't know which aftermarket gauge set you have, the voltmeter or amp gauge, or idiot light has power on the other side when the key is on. Voltage will back feed through that circuit. Is there anything connected to the IGN terminal in the fuse block?
Between 1 and 2 above, it looks like there is "stray" voltage on both sides of the fuse in that circuit. Voltage readings confirm this (with fuse removed). Does this mean I have a bad fuse block, or is there an alternate explanation?
I spent about 4 hours out in the heat trying to figure this out, would be appreciative of any pointers. I've attached my readings/notes.
Thanks.
#4
Somehow you are back feeding voltage to the relay causing it to stay engaged or its wired wrong.
Thanks for the reply.
I don't know which aftermarket gauge set you have, the voltmeter or amp gauge, or idiot light has power on the other side when the key is on. Voltage will back feed through that circuit. Is there anything connected to the IGN terminal in the fuse block?
I tried to figure out what devices have power and are connected to the gauge circuit - the ignition switch, the voltage regulator, and the light switch all do, but I don't understand how they could. I took readings on the brown wire to the voltage regulator hoping it would match what I was seeing at the fuse block but they were different.
#5
Try connecting the relay for the HEI through the IGN terminal or a key switched spade terminal in the fuse block.
The ignition switch pink wire supplies power the resistance wire as well as supplies power to both the GAUGE and the DIR SIG/ BACK UP fuses. The Gauge fuse supplies power to the TCS switch, idiot gen light, temp gauge, oil pressure gauge, fuel gauge, and parking brake/ brake level light. Again the gen light or meter circuit has the brown wire feed from the voltage regulator connected to it. If the fuse is pulled and the key is on voltage will flow through the meter and back into the circuit.
Its a pretty simple circuit and you should not have any back feeding unless you wired the gauge cluster wrong.
The ignition switch pink wire supplies power the resistance wire as well as supplies power to both the GAUGE and the DIR SIG/ BACK UP fuses. The Gauge fuse supplies power to the TCS switch, idiot gen light, temp gauge, oil pressure gauge, fuel gauge, and parking brake/ brake level light. Again the gen light or meter circuit has the brown wire feed from the voltage regulator connected to it. If the fuse is pulled and the key is on voltage will flow through the meter and back into the circuit.
Its a pretty simple circuit and you should not have any back feeding unless you wired the gauge cluster wrong.
#6
Background:
The car is a 68 w/ HEI powered by a relay triggered by the original coil feed wire. It also has aftermarket rally pack gauges installed, that function when the fuse is installed.
Symptom 1:
If the fuse in the "GAUGES TRANS" (lower right of fuse block) is installed, the engine keeps running when the key is turned off. It turns off fine when the fuse is removed.
Symptom 2:
With the car off, key in "run", and "GAUGES TRANS" fuse removed, the gauges have power. Not enough to function, they just move off of zero to a static spot.
Between 1 and 2 above, it looks like there is "stray" voltage on both sides of the fuse in that circuit. Voltage readings confirm this (with fuse removed). Does this mean I have a bad fuse block, or is there an alternate explanation?
I spent about 4 hours out in the heat trying to figure this out, would be appreciative of any pointers. I've attached my readings/notes.
Thanks.
The car is a 68 w/ HEI powered by a relay triggered by the original coil feed wire. It also has aftermarket rally pack gauges installed, that function when the fuse is installed.
Symptom 1:
If the fuse in the "GAUGES TRANS" (lower right of fuse block) is installed, the engine keeps running when the key is turned off. It turns off fine when the fuse is removed.
Symptom 2:
With the car off, key in "run", and "GAUGES TRANS" fuse removed, the gauges have power. Not enough to function, they just move off of zero to a static spot.
Between 1 and 2 above, it looks like there is "stray" voltage on both sides of the fuse in that circuit. Voltage readings confirm this (with fuse removed). Does this mean I have a bad fuse block, or is there an alternate explanation?
I spent about 4 hours out in the heat trying to figure this out, would be appreciative of any pointers. I've attached my readings/notes.
Thanks.
#9
What are the odds this car has a MSD ignition box? If so, unplug the regulator for the alternator, see if that solves your issue. If so you need to put a diode in-line with the brown wire to the alt warning light.
How about posting a diagram explaining how you wired your relay? You may consider supplying power to the HEI using the pink wire on the ignition switch. That wire will go to the same terminal cavity as the resistance wire in the bulkhead connector. Eliminate the relay, keep things simple.
How about posting a diagram explaining how you wired your relay? You may consider supplying power to the HEI using the pink wire on the ignition switch. That wire will go to the same terminal cavity as the resistance wire in the bulkhead connector. Eliminate the relay, keep things simple.
#10
No MSD box.
I ran the trigger wire to the relay off of a switched IGN terminal on the fuse box (for some reason I thought there wasn't one on this fuse box, I was wrong). That addressed the symptom of the engine run-on.
Doesn't mean I'm done (I still need to understand the what and why of the voltage backfeed), but at least I can drive the car normally and read the gauges
Thanks for the help.
I ran the trigger wire to the relay off of a switched IGN terminal on the fuse box (for some reason I thought there wasn't one on this fuse box, I was wrong). That addressed the symptom of the engine run-on.
Doesn't mean I'm done (I still need to understand the what and why of the voltage backfeed), but at least I can drive the car normally and read the gauges
Thanks for the help.
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garyfoust
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November 23rd, 2017 04:37 AM