Re: 1970 99e possible ignition switch failure/short - Saab Saab Model 99 Bulletin Board - Saabnet.com
NG900 & OG93 |
Vintage Models |
Clubs & SOC |
Other Cars |
Member Photo Galleries |
Member Directory |
*Buddy Registry |
*Mileage Registry |
What's New |
Photo of the Month |
I would say that generally you would not get a "short" per se inside the ignition switch, but there are several basic things to check. First, do you have a wiring diagram for your car? It will be very helpful - if you need one, contact me off-line and I can scan the one in the Service Manual and send it to you. Here are some other items:
1) Battery Cable (Large red cable from positive battery terminal to starter) - remove both ends, clean everything, reinstall, make sure everything is tight.
2) Negative Battery cable (braided flat cable), ditto remove both ends, clean, tighten. May also have an intermediate point on the body where the negative cable joins other ground wires from the wiring harness - make sure all those connections are clean and tight.
3) There are two large grey wires which connect to the positive battery cable, most likely at the point where the battery cable connects to the starter. One goes to the alternator and one goes to the fuse panel. The latter one is key - it is how battery voltage gets to the whole vehicle. Again, both ends of both grey wires need to be clean and tight.
4) Battery voltage (not fused, so be careful!) goes from the fuse panel to terminal #30 on the ignition switch via another grey wire.
So, make sure that all that stuff is in good condition and delivering voltage to the ignition switch. An important caveat (and common Saab problem) is that as wiring terminals get old and start to corrode and go through heat cycles, they start to loosen and for various reasons build up high resistance. So, if there is no load (open circuit) you may have a reasonable (eg: 12V) voltage reading, but the voltage may drop when you try to have current flow (such as when you turn something on). So, you will want to pull off terminals, make sure they are clean, and make sure they are tight when you put them back on.
It is also common for the ignition switch to get crud in it over time and then as you turn the switch the electrical contacts don't close or have high resistance so things don't come on. The other possible trouble source here is the ignition relay which turns on all the other stuff in the car in response to getting voltage from the ignition switch (brown and white wire from ign switch terminal 54 - or 34, hard to read the diagram). However, that should not prevent the car from running (I am assuming this is a carbureted car).
The ignition switch in crank position should send 12V to the start solenoid from terminal #50 through the yellow wire, and in the run position it should send 12V to the ignition coil from terminal #15 through the green and white wire.
So, if all the other stuff checks out OK, then go ahead and replace the switch (may want to clean the replacement switch with terminal/contact cleaner - Radio Shack - and lubricate the key part with graphite and the mechanical part with white grease.
posted by 50.48.9...
Posts in this Thread:
Post a Followup
No Site Registration is Required to Post - Site Membership is optional (Member Features List), but helps to keep the site online
for all Saabers. If the site helps you, please consider helping the site by becoming a member.
This is a moderated bulletin board - Posting is a privilege, not a right.
Unsolicited commercial postings are not allowed (no spam). Please, no For Sale or Wanted postings, SERIOUSLY.
Classifieds are to be listed in The Saab Network Classifieds pages.
This is a problem solving forum for over 250,000 Saab owners, so expect to see
problems discussed here even though our cars are generally very reliable. This is not an anything goes
type of forum. Saabnet.com has been a moderated forum since 1988. For usage guidelines, see the
Saabnet.com Mission and Purpose Page. Please remember that you are
not anonymous. Site Contact | Site Donations | Other Sites by SP -
Your address is: 126.96.36.199 - Using CCBot/2.0 (https://commoncrawl.org/faq/) - Logged.
Site Members do not see red text instructions, bottom of the page anchor ads, or box ads.
Click here to see all
the Site Membership Benefits!