SD25 Starting problems

SD diesels were widely available in the US in the 1981-86 Datsun/Nissan 720 pickups, and in Canada through '87 in the D21 pickup.

Moderators:plenzen, Nissan_Ranger

Highway Man
Joined:4 years ago
Location:Hillman West Australia
Re: SD25 Starting problems


Post by Highway Man » 4 years ago

Good Morning Plenzen!

I found the Warmers and removed them to check them out for further use, and in doing so I opened a tin of Worms as well,
I found the Lead connected to them had been cut off at number Four Warmer, between the Warmer and the Body Firewall" which might be a good
reason for them not to work at all!

I found the Little Green box with the "NGK" signs on it and traced the Harness forwards and up ,along the Firewall inside my cabin which then seems to
carry across the breadth of the Cabin and passes through the Firewall into the "Engineroom", along the righthand Mudguard to the Battery box and then
a left turn towards the Engine and "Number 1" Warmer and connects to Warmers numbered, 2,3,4, wear it is cut off,!

Now, Am I near right in my assuming, I can run a wire of simular guage from the cut off end and pass it through the "Firewall" to a pushbutton on my dash
and I might get a Warmerlight to turn on and by turning the "Ignition Key to on position, I might get the Warmer Light on my Dash to lightup?

and surprise me!

Best regards,

highway man!

Joined:13 years ago
Location:Cochrane Alberta Canada

Re: SD25 Starting problems


Post by plenzen » 4 years ago

That wire ends at #4 glow plug. When you turn the key on you should be getting power to that wire where it hooks to #1 glow plug. You should have power at #4 as well . If you do then there are no breaks in the wire. You would have to check this before the timer shuts it off. Did all the glow plugs heat up and the tips turn red hot when you applied 12V to them ? Hook a test light to #4 glow plug and turn key on and see if your getting power to the plugs (warmers) The dashboard light may not be working. My guess is that the glow plugs are coming on as its doubtful you would have got it to start when the weather was warmer. These little guys need that heat to get going. You do want to be careful with that NGK box you found and not cook it , if it hasn't been already.
Not the end of the world as you can do what Andy (nissan ranger) did and just go manual and bypass it all together.

Retired Pauly
Problem with being retired is that you never get a day off.
1987 D21-J SD25 KC

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