Starter connections SR71x

[PeterVarga]

Installed rebuilt Bosch starter. Anyone have a diagram? It makes a difference. Car starts and runs only when in the starter part of the key swich.

There is one tap on top. Then there is another that is covered with

a plastic cap. Then there is a screw terminal. I think one is for a car with an external ignition relay and the other is when you need the built in ignition contactor (latching.) Wanted to make sure which is which before I started connecting things.

I think I'll try to get the data sheet from vendor when I go there tomorrow. They should have included the diagram with the package when I purchased it. Dang these modern packaging techniques!

[Tiger75]

See my write up on Tii Register

http://www.thetiiregister.com/phpmyfaq/index.php?action=artikel&cat=19&id=25&artlang=en

Knowledgebase » Upgrades

: M3 Starter Upgrade

I installed an M3 Starter in my 74 Tii. My orginal starter still worked and was drawing about 30 to 40 amps but still seemed a little weak. With the timing properly set, during start up, the engine would slightly try to kick back or stall just before the engine would start. Rather than rebuild the orginal, I chose to upgrade. I finished the installation last night. The difference is amazing. Engine starts quicker and starter turns motor over with authority.

I did have one wiring issue that I have not figured out. I was unsure which of the small clip on wire went on the top terminal(black with red stripe). I installed it the way I thought it should go. The engine would start but would die immediately after the starter quit. I could tell the ignition was loosing power when the starter quit because the red light on my Crane 3000 ignition would go out when the starter quit. I swapped the top and bottom wires and the starter motor would turn but not engage. The starter might have been turning backwards but since the battery wire and the ground wire were not changed , I am unsure. But it did not work that way so I swapped the wires back.

Now the larger of two small wires was on the bottom terminal of the solenoid (50). The large power cable from the battery was on the large terminal 30 . This starter had a second terminal 30(not 15) on the top. The single black wire was connected here. I think this is the wire that is supposed to give full voltage to the coil and points during start up bypassing the ballast. When I disconnected this small black with red stripe wire, everything worked !

After starting the engine, if this wire was connected, the engine immediately died. It is like it shorted out power to the ignition. My electronic ignition gets its power from the coil, but I can’t figure out why connecting this wire would short out ignition. Well anyway If I just leave this wire disconnected, the starter works great! Should have done this years ago.

After study and playing with a volt meter last night,I have concluded that the M3 starter soloniod is wired differently than the stock 2002 starter for the smaller terminal 30 at 12 oclock. while the starter turns, the solonoid supplies 12 volts to this terminal but when starter is not turning with iginition on or off ,this terminal is grounded. Since the black wire with red stripe is meant to supply 12 volts to the coil during starting, the engine starts with starter turning. Once starter stops, black w/red wire is grounded at solonoid which grounds out the coil, which means no ignition - motor dies. My solution is to disconnect black w/red wire at both ends. My car has electronic ignition and I do not need a ballast bypass because I have no points.

I feel better now that I know what the hell was going on. My engine sure turn over fast now. It almost sounds like a real car!!

[PeterVarga]

That blog in the tii register was illuminating. It describes what I observe on my non-Tii '02. Thanks for the reference. Oh, and from the starting activity I get in the 'start-only' setting, its already seems worth it. More power than 30 year old original starter.

[PeterVarga]

Worked like a charm. Followed directions in write-pu and isolated the ground wire. Thanks Tii-Register and thanks for reminding me that they had those tech articles! This starter sound totally different than the other one.

---The reason I hesitated is that I think the Tii has an ignition relay and my '02 does not. But in this regard, I guess this modern starter is the same for both vehicles....Yay, it works!

[Dr. Thompson]

On 2/19/2008 at 11:16 AM, Tiger75 said:

See my write up on Tii Register

http://www.thetiiregister.com/phpmyfaq/index.php?action=artikel&cat=19&id=25&artlang=en

This is my first post! I have a ‘76 2002, manual transmission, 4-speed, with 49 states emissions and 32/34 Weber carb. I just replaced my stock starter with a Bosch SR71x starter. I have poured over this site and am not finding the solution, but the condition you describe here mirrors my problem. I wish I could access your write up on the link above, but I am finding that thetiiregister.com is no longer. I didn’t have the second top wire that you describe, and I don’t have an electronic ignition. When I turn on the ignition at the key, I get nothing. When I jump the starter, it attempts to start but grounds out, as you indicate in your post. When I disconnect the lower wire and connect another wire to the bottom post to the battery terminal, the engine starts and stays on. Any help is much appreciated! 

[John76]

Hi and welcome!

The Black/red wire attaches to the #15 terminal on the SR71x. The Black/white to the #50 terminal. I put a plastic cap on the other #50 terminal to prevent any accidental shorts.

Here is a picture of what it should look like.

 

[Dr. Thompson]

John76–

thanks for the quick reply! On my old starter, I only had the black and red wire connected, no black and white wires are visible. Can you help me by identifying where the black and white wires connect to from the starter unit?

[HBChris]

The lower 6:00 terminal is the trigger wire from ignition switch.  The 12:00 terminal was for a ballast resistor bypass during cranking only.  If this is a new lightweight starter do not connect anything there, it is live whenever car is running.

[Dr. Thompson]

1 hour ago, HBChris said:

The lower 6:00 terminal is the trigger wire from ignition switch.  The 12:00 terminal was for a ballast resistor bypass during cranking only.  If this is a new lightweight starter do not connect anything there, it is live whenever car is running.

It is the newer, lighter weight starter. I’m curious as to John76’s setup on the pic above and what Tiger75 previously stated that the 12:00 terminal has power when cranking but then switches to ground when the engine starts. This seems to contradict that, so I’m not sure I understand. Does anyone have a graphic that would show where the wires are coming from prior to connecting to the starter?

[John76]

1 hour ago, Dr. Thompson said:

Does anyone have a graphic that would show where the wires are coming from prior to connecting to the starter?

The Bosch SR71X is the latest (rebuilt) version of the stock '76 starter.

Here is a sketch of the wiring.  The Black/white comes from the ignition switch terminal #50 which activates the starter.

The terminal #15 on the starter solenoid goes to the + side of the coil. This supplies a direct 12V to the coil that bypasses the clear/green resistor wire from the un-fused side of fuse #12 only during cranking. Once the engine starts, the + coil is powered by the .9 ohm resistor wire...hence no external resistor is needed.

 

 

[Dr. Thompson]

3 hours ago, John76 said:

The Bosch SR71X is the latest (rebuilt) version of the stock '76 starter.

Here is a sketch of the wiring.  The Black/white comes from the ignition switch terminal #50 which activates the starter.

The terminal #15 on the starter solenoid goes to the + side of the coil. This supplies a direct 12V to the coil that bypasses the clear/green resistor wire from the un-fused side of fuse #12 only during cranking. Once the engine starts, the + coil is powered by the .9 ohm resistor wire...hence no external resistor is needed.

 

 

Thanks so much for the detailed description and the sketch!! In following the wires along, I noticed that the clear wire was cooked, and the #12 fuse was blown. After running new wire, I am able to turn it over (mostly) successfully!! The new condition I am observing is that  the starter sounds like it is continually running. I’ll do some homework to continue to troubleshoot.  Making progress...

[Dr. Thompson]

On 5/26/2021 at 5:16 PM, John76 said:

The Bosch SR71X is the latest (rebuilt) version of the stock '76 starter.

Here is a sketch of the wiring.  The Black/white comes from the ignition switch terminal #50 which activates the starter.

The terminal #15 on the starter solenoid goes to the + side of the coil. This supplies a direct 12V to the coil that bypasses the clear/green resistor wire from the un-fused side of fuse #12 only during cranking. Once the engine starts, the + coil is powered by the .9 ohm resistor wire...hence no external resistor is needed.

 

 

Thanks so much for the detailed description and the sketch!! In following the wires along, I noticed that the clear wire was cooked, and the #12 fuse was blown. After running new wire, I am able to turn it over (mostly) successfully!! The new condition I am observing is that  the starter sounds like it is continually running. I’ll do some homework to continue to troubleshoot.  Making progress...

 

Cleaned the battery terminals and ground cable at the engine block connection, et voila! Thanks again for your sketch—that did the trick!

[John76]

On 5/26/2021 at 7:37 PM, Dr. Thompson said:

I noticed that the clear wire was cooked, and the #12 fuse was blown.

The clear wire probably "cooked" when someone used a coil with too much internal resistance.

The #12 fuse supplies power to the electric choke, idle cut-off solenoid, and thermo-start valve on the Solex carb.

The unfused side of #12 supplies power to the + coil through the resistor wire. This unfused connection prevents the car from stopping if the fuse blows.

 

[VeroTii]

Just curious gentlemen.  What if the "clear" .9 ohm wire does has been replaced by a straight wire?  What happens?  I am sorting a 74 tii with lots of wiring foolishness.

[John76]

Jeff,

What kind of ignition system does your car have? 

The stock '74 - '76 cars used the "hidden" .9 ohm resistor wire with a Bosch K12V coil (2-ohm primary resistance) and a condenser & points in the distributor. A Black/red wire from the starter by-passed the resistor wire to the coil (+) only during starting (cranking).

If your car has electronic ignition module (e.g., Pertronix), the resistor wire is not needed, and often replaced (or supplemented) with a straight wire.

John