One of my 1990 Miatas has had occasional problems where it won't engage the starter. It's worse in hot weather, so this is the perfect time to troubleshoot :)
In the past, I have found numerous remnants of alarm installs, including multiple crap splices along the wire from the ignition switch to the solenoids. I replaced all of them including a length of wire that was almost all splices. I also bypassed the starter circuit on the ignition switch because buttons are more fun and I thought that might be it. No luck. I even rebuilt the switch.
Today, I was chasing resistance and finally found it. There was corrosion inside the female spade that connects to the solenoid. Enough resistance that sometimes it would trigger, sometimes not. And of course, heat bad. This spade is very well encased so it's very hard to see the corrosion.
A little happy time with the emery paper, some contact cleaner and some dielectric grease for protection and we're all good. Resistance between the ignition switch and the spade on the solenoid is almost zero.
Not easy to find, hopefully it gives someone else a hint when chasing a similar problem.
When I brought my Mustang down to Tampa it had been sitting at Dad's for 3+ years. Wouldn't start. I checked damn near everything, brought the starter in to AutoZoo, tested it, brought it back a couple weeks later and exchanged it despite it working (knew the manager decently well so he'd let me do dumb E36 M3 like that), checked and replaced the solenoid, recrimped half the wires that looked suspect, etc etc etc
Not a damned thing worked.
Finally I was doing something under the car and realized that where the the ground cable mounted to the aluminum bellhousing was completely covered in corrosion. Out came the roloc discs and 15-20 minutes later she cranked like there was never an issue.
Corrosion is the worst.
Trailer brakes didn't seem to be working yesterday. Thought the 12 year old controller might have died.
Checked the connector on the trailer that plugs into the truck. Yep... corrosion. Fixed.
Sometimes its the simplist thing.
I have the most wonderful tools, look like flattened tweezers, ends are covered with diamond dust. You can clean corrosion from female and male terminals with them.
In reply to Keith Tanner :
You mean old Miata's are learning from their British forefathers? ( Lotus Elan )
I just went through my Jaguar XJS and threw out over 100 pounds of wires and connectors. I know better than reuse old wires and connections. Since it's a race car the wiring is very simple and good connectors are readily available.
After more than 30 years, anything can age. The difference between the Miata and the Elan is that the Elan would have started showing this sort of weakness 20 years earlier :) Generally speaking I've found the Miata connectors to be pretty robust. Lucas bullet connectors are fairly easy to restore - but far easier to inspect.
I fully expected to find a degraded main battery cable - since the battery is in the trunk, there's a single cable that runs the length of the car. We have seen them develop high resistance in the past but luckily a check in the engine bay showed that wasn't the problem. The thing that made this one hard to find was the level of encapsulation of the connector, it's almost impossible to get a light on it and the plastic cover does not come off in the same manner as most. I suspect the design was specifically intended to minimize weathering effects.
Pete, I'm going to order a set of those tools. So much easier than emery paper on a female spade!
Thanks for posting this, Keith! I have a similar problem on my track car. I swapped out the starter after failing to locate a problem a year or two ago, and now it's rearing its ugly head again.
Any idea what those tools are called? They sound handy.
In reply to Mr_Asa :
92 5.0 Mustang about 5 years old at the time of this incident. I stopped for lunch about 150 miles from home. When I returned to the car it would not crank. After opening the hood I noticed the small ground wire from the battery to the body was letting out the smoke when I attempted to start. Without tools or a means to raise car I had AAA tow it to the Ford dealer. Soon, a young mechanic came into the waiting room and told me the starter was bad. I told him to remove the bolt connecting the battery ground cable to the engine block and clean the connectors. No start solved and the service manager offered me a job.
In reply to WonkoTheSane :
In reply to Pete. (l33t FS) :
IPA Tools makes them, likely where Matco sources them.
https://www.ipatools.com/product-category/tools/contact-care/
I normally use some contact cleaner. Might need to look into that tool set, too.
Tom1200
SuperDork
6/17/21 10:40 a.m.
That connector is one of the first places I look. My Datsun had a similar issue years ago.
EvanB said:
In reply to Pete. (l33t FS) :
IPA Tools makes them, likely where Matco sources them.
https://www.ipatools.com/product-category/tools/contact-care/
Just because they look identical (the Matco ones swing out like that too) and have 8040 in the part number?
Yep.
They were in a monthly flier, I said "ooh gimme", no idea how much they were. Saved my bacon enough times that they were worth it.
In reply to Pete. (l33t FS) :
Thanks Pete!
In reply to EvanB :
Thanks Evan! I'm ordering a set of those now!
Just to add to this subject, recent rustproofing sprays have caused me connection issues.
A few years back, I had a thread regarding a connection issue that cropped up after I had the car rust sprayed. One of the conclusions was the rust spray used was dielectric and got into the connection, disrupting it. After cleaning the connections the problem went away.
I have had the car sprayed twice yearly since then and have had no issues; until this spring.
When i got it done this spring immediately after, I had the same issue as before. This time with a different connection.
Keith Tanner said:
After more than 30 years, anything can age. The difference between the Miata and the Elan is that the Elan would have started showing this sort of weakness 20 years earlier :) Generally speaking I've found the Miata connectors to be pretty robust. Lucas bullet connectors are fairly easy to restore - but far easier to inspect.
I fully expected to find a degraded main battery cable - since the battery is in the trunk, there's a single cable that runs the length of the car. We have seen them develop high resistance in the past but luckily a check in the engine bay showed that wasn't the problem. The thing that made this one hard to find was the level of encapsulation of the connector, it's almost impossible to get a light on it and the plastic cover does not come off in the same manner as most. I suspect the design was specifically intended to minimize weathering effects.
Pete, I'm going to order a set of those tools. So much easier than emery paper on a female spade!
I wonder if The Lotus Elan was still being built, any bets on if the wiring would be upgraded?
I know Jaguar's have had several up grades since those days.
In reply to Pete. (l33t FS) :
That's cool as hell. Thanks, David for the other post describing this solution- I didn't see this depth in the thread. I think I need some of them.
This is also why I am addicted to dielectric grease. It keeps connections from corroding. When putting the new harness in the Bugeye, All the Lucas bullets got a dose.
Ok had an E30 some years ago. Going through the car cleaning contacts and adding dielectric grease woke up just about all the things that didn't work when I got it.
The grease keeps moisture and oxygen away from the conductive metal contacts. Makes it go a lot longer before going bad.
So this showed up yesterday. Watch out corroded terminals!
