Interesting electrical issue

[franbev]

I took out my battery to coat the battery box with a rust sealant. While the sealant dried I charged the battery since my '74 Ascona gets little use. After replacing the battery and starting the car I noticed that the amp warning light on the dash was dimly on. After a couple of restarts and with no change I noticed that when the key is first turned to the run position before going to the start position the dash warning lights failed to come on as they usually do. After starting, pushing the brakes or engaging the turn signals causes the amp light to shine brightly. I'm guessing it's the voltage relay, unplugging it causes the amp warning light to go out. Any other tests I can run to diagnose the issue? Are regulators easy to find? If so where?

[markandson]

Did it do this before you took the battery out?

[GoinManta]

Battery ground wire that goes to the firewall is probably coated and making a weak connection. It's a definIte ground issue..

[franbev]

No, it did not do this before I took out the battery. As to the ground wire to the firewall, is that the small gauge wire in addition to the main at the battery lug?

[GoinManta]

Yep, that one..

Clean the threads out.. and add a clean bolt..

I would also check the small wire from the case of the alternator to the block is good and tight and clean.

Also see if you have a good ground cable from the block to the body..

[markandson]

Originally Posted by GoinManta Battery ground wire that goes to the firewall is probably coated and making a weak connection. It's a definate ground issue..

This is where I was going also, just wanted to check if it was a new issue or not. Go after the connections that were moved when you changed the battery. It could be a bad battery cable. Sometimes the cable corrodes inside the end connectors at the battery and you can't see anything from the outside but you have a very high resistance connection. Before you go crazy chasing demons I would do the simple thing and replace the cables and check the grounds elsewhere in the engine compartment.

[wrench459]

Don't forget about the engine block to chassis.
John hammered that one home with Gene's Opel.
No engine ground, no alt ground, no charge.
Voltage drops don't lie.

[RallyBob]

Originally Posted by wrench459 Don't forget about the engine block to chasse. John hammered that one home with Gene's Opel. No engine ground no alt ground no charge. Voltage drops don't lie.

Yup, and if you have a Pertronix you will find that the skinny black ground wire for the Pertronix unit is your only ground without the main ground strap...and it will very quickly melt and disappear if you start the car!

[franbev]

My Ascona has no Petronix and the poor grounding makes sense. To test that I hooked up a jumper cable to the negative battery lead, making sure to make contact with the smaller lead to the body, secured the other jumper to a variety of "good" grounds then started the car and it had no affect. Dimly lit battery symbol still. The negative battery connection to the block is good enough to let the car start easily. Any other ideas?

[Opelkurt]

Check the fuses, just in case. I can remember the alternator light acting the way you've described when the last fuse to the right (or maybe left?) was blown, or if the fuse clip was weak and made poor contact. If the fuse is known to be good, give it a jiggle with the ignition on but the engine not running to see if the alternator light will come on. It's worth a try at this point..

-Kurt

[wrench459]

Originally Posted by RallyBob Yup, and if you have a Pertronix you will find that the skinny black ground wire for the Pertronix unit is your only ground without the main ground strap...and it will very quickly melt and disappear if you start the car!

Hee Hee there is another possible ground point. The throttle return spring.

[franbev]

Eureka! I checked the fuse for power and there was continuity. However, looking closer i noticed that the little fuse clip had broken free from the fuse panel? Who'd of thunk! Now, how do I re-attach the fuse clip holder? The bottom one looks like it's staked or spot-welded, any way to put a very small screw thru the fuse clip to the panel? Thanks again Opelistas!

[wrench459]

Cool you found the bugger.
Sure put a small screw or bolt to get a good mechanical connection if you can. Then a small amount of silver solder should make it good to go.

If thats not possible an inline fuse.

Now you know the pitfalls of test lights!!!!!!

[myopels]

Originally Posted by wrench459 Don't forget about the engine block to chassis. John hammered that one home with Gene's Opel. No engine ground, no alt ground, no charge. Voltage drops don't lie.

There is also another thing you might keep a lookout for is the battery cable ends that have 2 bolts to clamp the wire. OI found out the hard way that they are junk. I replaced a perfectly good starter and relay before en electrical engineer showed me that the wires inside corrode, but the outside looks good. Moral- get BIG cast ended wires and no problems!

[RallyBob]

Originally Posted by franbev Eureka! I checked the fuse for power and there was continuity. However, looking closer i noticed that the little fuse clip had broken free from the fuse panel? Who'd of thunk! Now, how do I re-attach the fuse clip holder? The bottom one looks like it's staked or spot-welded, any way to put a very small screw thru the fuse clip to the panel? Thanks again Opelistas!

It's a pretty common issue, I've been fixing fuse boxes for these cars for as long as I've owned them! Most of the time if it's not too bad you can simply re-attach the clip with a small brass screw and nut. Other times it's so corroded you must either repair the piece or replace it with one from a donor car.

The last time around for me, I replaced the OEM glass fuses with a modern blade type 'mini-fuse' holder, but I retained the OEM wiring and fuse block. I posted some pics in the Manta/Ascona social group, if you look at my last two posts on this page.

[franbev]

Could I use a small diameter "pop rivet" to secure the blades? This way I would'nt have to get at the back side of the fuse block assembly.

[markandson]

Originally Posted by franbev Could I use a small diameter "pop rivet" to secure the blades? This way I would'nt have to get at the back side of the fuse block assembly.

Possible yes but you might crack the fuse block, good idea in the short term yes, good idea as a permanent fix, no. The dissimilar metals will interact and even aluminum by itself will oxidize and cause heat at the connection over time. Since this is one of the fused connections maybe you could add a connection to the non-fused side of the terminal block and then use an inline fuse to fix your problem. The fuse block also just snaps into the bottom of the fuse box so if you can find a good fuse block you would just have to unplug all of the wires keeping track of where they go and then replace them on the replacement block. A real PITA yes but it is possible, I have put wire numbers on all the wires and have a diagram showing myself where each wire goes. You could pull my entire fuse block apart and I could get it back together in about 1/2 hour.