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TR7 No Cranking Problem

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William Smith

TR7 No Cranking Problem
« on: October 07, 2017, 09:53:22 PM »
My '80 TR7 is no longer turning over. It began last month. First time, I turned the key twice and nothing (no clicking or any other sound) although dash warning lights seemed to come on normally. Then on the third try it started normally, I drove it to the gas station, gassed up, and started normally for the trip home. A week later, turned the key once and again nothing. On second try, it started right up and I drove it 80 miles, parked it for seven hours, then it started normally for the 80 mile trip home. Didn't try to start it until this past Wednesday (about 2-1/2 weeks after parking it in the garage and it wouldn't crank no matter how many times I tried. Same thing today. Before I embark on trying to locate the problem, several initial questions for the group:

1. Is there any specific problem unique to TR7s that would cause this?

2. I looked at the wiring diagram (which is mostly incomprehensible to me) and noted that there is a "starter relay". What is that relay's purpose? My TR6 has no such relay.

3. If it turns out to be the starter/solenoid, what has the group's experience been with the newer high-torque starters?

B  B - Are they an exact fit?

B  B - Will the stock heat shield fit on them?

B  B - How do they hold up?

B  B -A number of vendors carry them. B Are any vendors' starters better than the others?B

B  B - Anything else I should know about them?

Any info will be appreciated.B

Thanks,B

Bill Smith

'80 TR7 DHC

'72 TR6







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dave1massey

Re: TR7 No Cranking Problem
« Reply #1 on: October 07, 2017, 10:21:59 PM »
There are a couple things that can cause this problem.B  One is a bad starter relay.B  It is one of the relays at the fuse block.B  Another is the starter interlock jumper on the transmission harness.B  The third is the starter itself.B B

Since the lights light up when you turn the key the relay is energizing but it may have a bad contact.B B

The wire harness is set up for auto transmission and there is a neutral interlock switch on those.B  The manual box harness has a jumper in that location of the connector.B  If the contacts get dirty they can cause the no crank problem.B  Find that connector and unplug and replug it to clean off some of the oxide.

The most expensive part (and hence the last thing to swap out) is the starter.

If you have a test lamp you can see if you are getting voltage at the solenoid wire.B  If you are not check elsewhere first.

Dave MasseyB





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William Smith

Re: TR7 No Cranking Problem
« Reply #2 on: October 08, 2017, 03:37:50 PM »
Thanks Dave. Regarding the starter interlock jumper - where is it physically located, and how do I get to it?This possibility intrigues me (especially if it's open to the weather) since the problem arose shortly after driving through a heavy rain storm on my way to the VTR convention in Princeton. It first occurred the next time I tried starting it after returning from the VTR.Thanks again.B Bill SmithSent from my Verizon Wireless 4G LTE smartphone---

dave1massey

Re: TR7 No Cranking Problem
« Reply #3 on: October 08, 2017, 03:57:35 PM »
Oh, sorry, I was going to mention that. There is a branch in the main harness that feeds down past the firewall.B  It connects to the harness on the transmission.B  This harness connects up the reverse switch and it connects to the neutral safety switch on the auto box.B  The manual box harness has a jumper.B  It is located generally above the oil filter on a TR7.

Dave MasseyB





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"Jim Morrison"

Re: TR7 No Cranking Problem
« Reply #4 on: October 08, 2017, 07:55:36 PM »
I can't help chiming in here. A couple of days before heading to Triumphfest inFlagstaff,  my '79 TR7 started doing almostexactly what William described.  I'd turn the key- dash lights would come on but no starter.Perhaps on the second or third turn of the key -it would start right up.  There would be nohesitancy or slow turning of the starter, itturned over just like it should have.  It seemedinfrequent and intermittent at first.  I decidedto wait and see if it would get worse.  At Triumphest - after the first autocross  - itquit - wouldn't start, not to mention a crap loadof other issues which I couldn't touch 'cause thebloody car wouldn't start.  After much effort - lots of advice - I was told ofthe harness jumper wire for the Auto Tranny - forthe Neutral Safety start switch.  Since wecouldn't get under the car - my coaches had meopen the fuse panel up and pull the starter relayharness out to where I could see the wires withthe thought of putting a jumper wire between thetwo white / red striped wires.  Before I did this, I noticed I had a spare starterrelay in the glove box.  I pulled the old relayout and the new one in - and voila -  it startedright up.  STARTER RELAY.  The old one would even click, it just wasn't doingwhat it was supposed to be doing.  I was lucky tohave a new one on hand.  Guess that's why Icarried it with me.  Don't overlook the relay - check it first. Jim Morrison

dave1massey

Re: TR7 No Cranking Problem
« Reply #5 on: October 08, 2017, 08:09:29 PM »
That makes sense.B  That contact carries the solenoid current and that is an inductive load so each time you release the key there is an arc across the contacts.B  Over the years the contacts burn up and stop carrying current.Easy fix if you have a spare relay.Dave MasseyB Sent from my Verizon, Samsung Galaxy smartphone---

kddpowercentre

Re: TR7 No Cranking Problem
« Reply #6 on: October 09, 2017, 04:47:18 AM »
Had the same problem in the late 1990's, turned out to be mechanical not

electrical.



The starter motor solenoid centre bit that operates the contacts and

pulls in the pinion, slides in a thin wall brass tube. Now with engine

vibration over 20 years, it hammered a dent in the tube, stopping the

shuttle from moving, thus no operation, no noise and random operation.



Brian



77 TR7 4sp



77 TR7 5sp

Dave

Re: TR7 No Cranking Problem
« Reply #7 on: October 09, 2017, 07:30:42 AM »
I may very well be the starter.  But a starter costs $200 and changing it out means fiddling with the exhaust system and if I went through all that just to find out it was the starter relay I would kick myself.  (BTDT)  That is why I recommend checking out the transmission interlock jumper and starter relay first.  These are a lot less expensive and a lot less work.





 Check the easy stuff first.



 



Dave Massey

kddpowercentre

Re: TR7 No Cranking Problem
« Reply #8 on: October 09, 2017, 10:18:26 AM »
If it is the starter, hit it with with a hammer, relocates offending

item and normally works.





Brian



77 TR7 4sp



77 TR7 5sp

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