Immobilizer Problem (I think)

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First posting more to come

All while chasing  head lights not working,  I removed both Ignition and lights relays.   This unit also fell out of dash.  chip was taped in, and siliconed in  but dry so fell out.

In my wisdom did not think about it. Long story short headlights work but car does not start.  Switch turns on and pump primes, ck engine also registers but no starter,

Checked both USA7s and Caterham & Lotus Seven Club for info.  Found info on resetting but not working, suggestions

[22 of 40]

All,

Have positioned the sensor with chip orientation in correct position to start.  Kleenex and duct tape to test for week. then more silicon..

Have read about a manual switch and  wiring by pass. 

Any thoughts

Thanks in Advance

Rick

 

Next project Radiator Fan

I've put in a manual switch  directly to fan so works great, but not part of system

[MV8]

Unclear. What did you read exactly?

Why bypass the fan circuit?

[22 of 40]

Fan never comes on, I understand that the ecm activates fan relay, but just starting that trace.

Temp gauge is working, so turn on the fan manually.   Central Texas heat rt. now starts at 80 degrees morning thru 115 in afternoon.

Only an hour check time in morning when cooler.  Still looking for sensor, no temp sending unit found near heater core or other water pathways, so far, This has a 1.6 l sigma dohc in it

[MV8]

I don't think it is controlled by the ecu.

Check the radiator for the fan thermoswitch (remove nose) or just follow the wiring from the fan motor. One of the two wires should go to the fan thermoswitch and the other goes to the relay. The thermoswitch should come on/short at about 197f/92c to ground the fan relay located with the other relays in your pic. Should be on the end of the bank of relays.

If controlled by the ecu, just following the fan motor wires should determine that.

[22 of 40]

Thank you,

Will start tomorrow morning.

Rick

[MV8]

I expect the fan switch to be next to the upper radiator hose in the top of the radiator. Check for a ground on one of the connectors. Touch the other connector to ground with the key on and if the relay and other wiring is good, the fan should come on. You may need to remove the ground wire eyelet from the chassis, wire brush the chassis and eye, then reinstall for a good ground.

If the coolant is too low, the fan switch won't be submerged and won't feel the heat. The clear coolant filler tank/expansion tank on top should always have the coolant level visible.

The fan switch is a very common part for vw/audi/porsche and easy to find here for around $10. Here is a link to the switch I think you have (reference # 823959481F, TS-151): https://caterhamparts.co.uk/cooling-fans/38-cooling-fan-switch-thermostatic-rad-fitment.html

https://www.summitracing.com/parts/smp-ts151#overview

If you want to bypass as a back up to a failed relay or switch or low coolant level (to keep the fan engaged until you reach a source of coolant), A switch rated for 15 amps at 14vdc and 12-14ga wire should be ok for the standard cooling fan.

Edited August 12, 2023 by MV8

[22 of 40]

Only temp sensor found, is located underneath the coil pack for engine (see pics). 

Was able to remove wired socket and as expected dash gauge went to high when turned on.  As gauge works normally when plunged  in,

I'm not inclined to replace the sending unit right now.

 

Engine and harness came from a 2011 Fiesta and tied into the caterham chassis harness.  I also believe the ecm came out of the Fiesta.

 

Thanks for all the good imput

Rick

 

 

img20230812_15244881.pdf

[MV8]

Can I see a pic of the radiator and fan?

How did you determine the "easy car electrics" pdf is for your car?

If the builder used the fiesta ecu to control the fan, the oem programing may not cut the fan on until 215f or so for better emissions. You may want to replace the plug in the radiator next to the upper hose for the 197f sensor to control the fan through the relay the way Caterham designed the harness for a sigma.

 

Fan ON temps are typically 12 or so degrees higher than the OFF temp which is a little higher than the thermostat opening temp that sets the minimum operating temp. A fan temp too close to the operating temp would come on once and never shut off until the engine is off long enough to cool down.

 

EDIT: Found a pic of a rover powered sigma and a link to an upgraded radiator for the sigma with a similar fan switch location: https://www.coolexperts.co.uk/product/caterham-sigma-engine-uprated-aluminium-radiator/

 

 

Edited August 13, 2023 by MV8

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Here are the photos1.

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Sorry for read.  1.  is back side of radiator 2 is only port, outside of hoses and too high if air in system  3.  fan plug connection, runs to light harness and back toward firewall.

Easy car electrics for ref only, the sensor only talks with the ECM which controls temp gauge and should control relay

I,ve wired fan   BATTERY B+/ SWITCH/ FAN /BODY GROUND B-

AGAIN THANKS

[22 of 40]

This diagram that I saved has also been in my thought process from one of the S7 groups

img20230813_11261905.pdf

[MV8]

You're welcome. Are you all good then or are you looking for feedback on something?

Edited August 13, 2023 by MV8

[22 of 40]

We,re good

Many Thanks

Rick