Crank no start. No lights on dash

[craigsmith86]

Afternoon all,

I'm several months into an engine rebuild and refresh on my '86 Mk1a. Engine is sorted, installed and ready to go but I've run into an electrical issue that's left me puzzled.

Here's some background:

After refitting the engine loom I had heat and smoke coming from the ground strap on the head (fitted on the engine hanger near the timing cover).

I immediately disconnected the battery and replaced the earth. Investigated the earth issue and stupidly realised I'd painted the transmission and starter motor earths points without cleaning them off. Cleaned all reattached the earths.

Car now cranks strongly and has fuel pressure at the rail but has no spark whatsoever. When the ignition is 'on' there are no dash warning lights (besides handbrake) but all other interior electrics are working fine. The coil pack and the igniter pass the inspection steps in the BGB.

Assuming I had burnt something in the loom(s) I removed both the engine loom and the loom that runs from the boot, to the fuse box that terminates in the passenger kick panel. Both looms has signs of wires being hot (which may not have been related to my issue) so I replaced both looms with second hand ones from a working car.

Same issue. Crank. Not spark. No warning lights.

Next thought was a fried ECU so today I've replaced the ecu like for like. Same story.

I'm now at a total loss. Everything I expect to be working is working except the dash lights and spark.

I would like to go through the loom wire by wire from the ECU but I only have access to an 88 BGB which has different pinouts on the ECU so diagnostics is pure guesswork. Any advice would be much appreciated. I really want this car back!!

[jimi]

Sounds like a fuse or bad wiring. Have you checked all the relevant fuses in the engine bay, drivers footwell and front boot fusebox's ?
A PDF copy of the Toyota Electrical Wiring diagrams is available in the Downloads section https://mr2oc.co.uk/downloads/technical-stuff/mk1.html which will be accurate for your car (it 's the best electrical manual I've found for UK/EU MK1's)

There's a junction box hidden in the driver's footwell up behind the dash (it's shown in the above manual as JB3) it's been known to suffer from heat damage caused by overloads, bad/slack connections or even an incorrectly connected battery.